Mahiru-no-Yo

Mahiru-no-Yo (真昼ノ夜) is a possession-type demon of the Black Demon Series. She is Guren Ichinose's former human lover, Mahiru Hīragi, who sealed herself within a sword and became Guren's Cursed Gear.

Appearance
Mahiru-no-Yo appears exactly as Mahiru with the exception of having fangs and red eyes due to having been a vampire when turned. She is the only demon who does not have pointed ears or horns unlike the others. Later will she becomes horns in Black Demon Scenario. She still wears the female First Shibuya High School uniform, a sailor fuku.

In her sword form, she appears as a black katana with a glowing crimson, red streak that is outlined down in the middle portion of the blade.

Anime: Mahiru-no-Yo is portrayed to have a more saturated hair color, and the size of her breasts are toned down more.

Personality
Merged with the demon in his sword to become Mahiru-no-Yo, being a possession-type demon suggests she is particularly violent. She helps Guren grow into a namanari and possesses him as needed to make Guren's demonic side take control; however, Mahiru-no-Yo's balanced demon and human personalities she had as a vampire remain as she does not appear to be as twisted as when she used to be as a namanari such as being able to make calm and rational decisions. She also retains her love for Guren and Shinoa, though twisted as she seeks to turn the former into a demon and hoping for the latter's love will awaken her demon to so that she can become stronger.

Having said that, Mahiru-no-Yo shows concern for them, particularly Shinoa, whenever Shikama Dōji is involved as when she told Shinoa to hang in there to save her from the possession. Mahiru-no-Yo also showed that she does have a softer side towards Guren, taking time to comfort Guren genuinely when he was about to become a demon over his furious guilt of causing the Catastrophe, even taking responsibility for it along with him, and showing sombreness as Guren notes on his regret over being unable to save her, and even seems to show some concern towards Guren's Squad, as she silences Noya when he tempts Guren to reveal the truth, which will kill them, and tries to give Shinya a reassuring smile.

History
Mahiru-no-Yo was actually Guren's previous demon, Noya Hienma. When Guren threw away Noya, Mahiru picked up the weapon and stabbed herself with it in the heart where she merged with it which was what Mahiru had planned all along. Noya was unable to stop the curse from spreading and eventually Mahiru was sealed/fused by Noya thus transforming her into Mahiru-no-Yo. She became the demon within his Cursed Gear and part of the Black Demon Series.

Events of 2015
At first Guren had no idea what is contained in his sword if it was Noya's or Mahiru but he knew that Mahiru did absorb Noya, though he is unsure. However he can feel his demon power in his sword, which Guren mentioned it's stronger than before, and Guren keep lying to his friends about her disappearance. In Guren dream, Mahiru sat across the river on the opposite bank. A smiling Mahiru glared at Guren in silence as he and his friends were having fun. After Guren wakes up, and Kureto's long interrogations, he tells Guren the demon inside him has advanced to a stage beyond their current technology. Guren demands if Mahiru is inside him, Kureto denies it saying only a demon lives inside him. Kureto finally tells Guren that he is been hallucinating much to Guren confusion. Kureto explains his dream that his demon is making him hallucinate what he wants to see. Guren denies him but Kureto says this is the result of their readings.

Later Guren lies to Kureto that he already killed Mahiru and she disappeared into him which was his last memory in the underground lab. Kureto explains that he drugged Guren and found out that his demon is out of control to the point that his levels are off the chart, but yet he remains totally sane. He thinks that Mahiru did this to him. With the interrogation still going Guren asks Kureto what's going inside his body, with same answer, Guren questions if why can't he hear his demon voice but Kureto explains about developing a drug to bring demons under their control, suppress them.

Guren tries calling out his demon but says Noya to no avail nor response, though he still feel his demon supplied him with power, and Kureto was surprised by Guren's demon power when their swords clashed. Guren sheathes his sword after their brief clash. Later Kureto produces a syringe to use it to talk to his demon.and finds out that Guren's hand are resisting the drug, forcing Kureto to inject him. Though he struggled and mentions it's not working, when the drug finally started to work. A Guren apologises for the trouble, Raimeiki tells Kureto that's not Guren but the Guren silences Raimeiki and Kureto questions if he is the demon or is he Mahiru, Guren is revealed to be possessed and conforms so.

Kureto questions the possessed Guren several questions but he brushes them away, and when he says he doesn't want to disappear, Kureto shuts up Mahiru whom she laughs, and Kureto informs her about the drug that will bring their demons under their control. but the possessed Guren laughs ridiculing his statement. Kureto tries to get a hold of Guren to bring him back, he conforms he is but suddenly insanely laugh then Guren began clutching at his head and black out.

Guren then still wonders if Mahiru is inside him but Kureto again says only a demon is inside him. When Guren tries to talk to his demon Noya, finally a voice responded although Guren noticed the voice didn't come from his mind but from the window in the classroom. As he saw Mahiru-no-Yo for the first time sitting on the windowsill, though he noticed only he himself can see her as Kureto couldn't. Guren lies to Kureto by saying that Noya did answer him when Kureto asks him if he remembers what happened, Mahiru-no-Yo speaks to Guren from the window to tell Kureto the Imperial Demons had killed her and he did went berserk. Though Guren had doubts what was going on and he had no choice but to listen to her words.

He did tell Kureto what Mahiru told him and when Kureto keeps giving him a series of questions, Guren simply obeyed Mahiru instructions until Kureto becomes satisfied. Calling the experiment is over and he releases the illusion in the classroom. and Mahiru says to Guren he should be glad since he trusted her, but she is ignored. Later Mahiru was standing beside Shinya making him hard to focus with by their chat, she tells Guren that she is real and not be afraid, with a promise, and asks if he is glad that he said what she has told him to because she knows Kureto more than him. She then goes to sleep, telling Guren good night and she vanishes.

Later when Mito was talking to Guren, suddenly Mahiru talks to him in annoyance and with jealousy if Guren would be with Mito from now on (as he was with Mahiru all these years), she is ignored by Guren. When Mito says she was fine with the idea of her never loving her. Mahiru gets annoyed and abruptly tells him to to do what she wants adding if he haven't hurt her enough already. Continued to be ignored and Guren keeps talking to Mito that they recently took the drug and couldn't think correctly as her face fell on his lap, Mahiru says to Guren when she remembers the time both of them did the same thing is just the reason that Mahiru wasn't precious to him.

Again ignored, Mito asks if they didn't take the drugs, if he would sleep with her, although Guren doesn't mind so, causing Mahiru to think if this is really what Guren thinks that he didn't need her body in their days together, and she simply just couldn't live without it. Yet ignored by Guren. When Shinya and Guren keeps talking about the meaning of life and if life has a meaning back and forth, Mahiru-no-Yo questions Guren to give him a good answer going on as she just wants to help him. Guren doesn't believe her and even asks her if she knows the meaning of life, to which she conforms so and tells him that the ones he resurrected, which is Shinya and the others only have 10 years to live as well as she will tell him the way to save them.

Guren thinks she is lying and she is simply a demon who is just trying to take control of him. She denies her lies and he is still dancing in someone's tune but then reminds him that there is a vampire headed their way. When Shinya was about to attack the vampire she tells Guren for Shinya to hold his fire as he has business with the vampire.

Guren calls Mahiru-no-Yo wanting to know how to save Shinya and the others, she materializes beside Guren accepting his request and says they've got a lot of work to do.

In Meguro ward of Tokyo, near Gakugei University station, Mahiru-no-Yo speaks to him, mentioning that he has no shame, as he gets aroused even at times like these as he is descends from the stairs headed towards the vampire. Guren asks her meaning, answering him with an example of how an existential would drive someone when they are near death. Then Guren tells her if he is going to die but she says, she won't allow it and Guren thinks he is afraid.

Mahiru states there won't be a fight with the vampire, only speak to him for Shinya and the others sake to save them. Guren asks her about the vampire, but Mahiru is clueless as she never seen him before, and Guren wants to know his situation to have a discussion with a vampire that Mahiru herself doesn't know. Though she remarks, about a possibility that the vampire is a conduit to someone else nor he is simply passing by at a wrong time, in which case it would be a bad idea to talk to him.

Guren finally arrives at the ground floor while the vampire awaited him outside, and he asks Mahiru that he doesn't understand the situation if he should approach the vampire, besides Shinya is on the top floor, she already knows that Shinya is ready to shoot the vampire and questions her if killing the vampire would cause trouble, to which she doesn't know herself.

Mahiru-no-Yo states also there won't be a problem if he see's him talking with the vampire, and lectures Guren that a vampire would care less if he finds out that Shinya and the others are resurrected, as well as mentioning to Guren if he doesn't mind that Shinya would be wiped out of existence. However Guren tells her he does mind and she says if he does so, he should better take care of it.

With a resolve, Guren tells her he will take care of it, which makes her glad. After spotting the vampire, Guren hid behind the building wall. He placed his hand on his sword and Mahiru-no-yo remarks how Guren feeling that he has to kill the vampire, she says it is his intense bloodlust. As he drew his sword he says to Mahiru it's their opportunity which she has the same opinion as him.

After a quite chat with the vampire, Guren kept thinking to himself about the tragedy that happened in the underground lab. Wanting to avoid the truth that Mahiru killed all his friends, he hallucinates to himself that it was his doing with Mahiru manipulating him. Mahiru-no-Yo interrupts his thoughts, saying if it does matter if it's the truth, as either way it doesn't change what he has to do. Guren says not to read his thoughts, she denies doing so as he was speaking out aloud, and heard everything.

Guren then as from this point he will close his mind off her. She tells Guren do as he wishes though it won't change his hopes and dreams. For him to buy more time for Shinya and the others as well as for her to bring her back to life as well the world itself back to life, before she continues Guren shuts her up though she continues her words what Guren really wants is to be freed from his guilt, which is his only his purpose in life, his desire, and finally says the time has come to speak with the vampire.

Later when Guren was talking to Saitō he wants to know what he did to Mahiru, and blames the latter for turning her into a vampire though Saitō informs him she isn't a vampire either and Guren demands what he did to her, to which he answers exactly what she wanted; she swallowed a demon and went inside him. Guren then levelled his sword at Saitō's throat asking again what he did to her, getting the same answer, that Mahiru herself wanted Guren to survive, confusing Guren, Saitō states Mahiru wanted to become his strength and support him from within (Mahiru-no-Yo) herself. When Saitō takes out a Sinful Key dagger out of his breast pocket, Mahiru-no-Yo however materialized next to Saitō. Although unable to see or hear her, Saitō did mention he senses a presence asking about her location. She conforms so but also says she wouldn't able to hear him, but Guren informs him that she's standing next to him. Though he expected as much, asking what he will use the dagger for, not telling him as it's for him to know, instead he asks Mahiru contradict so. Saitō then pierces Mahiru's throat with the sinful key, she gives a short cry, and puts her hands on her throat then she collapses to the ground. Guren screams demanding what did he do to her, but Saitō simply says he hid something which is a sin.

Mahiru-no-Yo then turns towards Guren reassuring Guren that they will encounter Saitō again after he departed, he also left a letter for Guren. Warning Guren not to look at her, since Shinya is with him as well, and he will notice. Advising Guren to pick the letter without Shinya noticing.

By passing off Caek, Mahiru-no-Yo suddenly gives a comment to Guren that most of his desires are guilt. As she sounded disgusted but Guren ignored her.

She talks again when Guren was about reach the letter Saitō left him which he put it in his pocket, asking if he is going to read it now, but she is ignored. She however informs him that she is feeding off his desires to know the secret even as they speak. She says that she loves Guren, being so happy that she's inside her.

Much later, Mahiru-no-Yo materializes wanting to speak with Guren, asking if it ever occurred to Guren that sleeping with her is a punishment, confusing Guren, and she tells him it's a forbidden love, wishing to do it again. As his body only wants to ravage with her, kill her. Guren in return says she only exist inside his mind as a fantasy. She does comply with. However Guren still believes that she is just a hallucination that was created by his demon, and she says that she is a demon. Questioning how is it even possible to sleep with a fantasy. She starts to tease him, annoying Guren. She laughs, Guren suddenly wants to know if she is real, though she cuts him off, saying that she already proven that by telling him a vampire was coming. Guren thinks to himself about how demons work and their personality, however she cuts him off as this is his mistake, Guren is annoyed as he thinks that she can read his thoughts.

Mahiru-no-Yo remarks she can't read Guren's thoughts, as he built a wall around his mind. and she would share information with him if he would lower those walls. Guren denies her, not wanting to be her puppet, and she says the opposite. As she tries to come closer, Guren takes a step back in return she laughs and calls him a scardy-cat but Guren informs her, he can't be blamed for being scared of her, being a genius and all.

She wants Guren to conquer his fear as humans can only become stronger if they face their fear, Guren mentions she did conquer her own, shedding away her humanity as well. Mahiru-no-Yo shots back the same to Guren, when he says he is human, she laughs and repeating it, she laughs more. Guren inquiries Mahiru-no-Yo about Saitō's words told him, which she is clueless about it. As even their first encounter was planned, Mahiru-no-Yo says everything was planned as everything was 100 years ago.

She tells Guren if it makes them soulmates, but Guren doesn't find her comment funny, he tells Mahiru-no-Yo he will lower his walls on his mind for a moment for information, however she notices Shinya's sudden arrival, as she vanishes and teases Guren in his mind.

A boy named Kuro Kuki and his friends who loathes the Ichinose clan, seeing Guren as one, annoyed he challenges him outside of Guren's apartment in the outside barracks. Mahiru-no-Yo then informs Guren in his head about his strength, and says to her he guesses so he can handle it, she thinks that Guren might lose, and he asks her if she would be on the same boat as giving up. She however simply says, she insanely loves him. Mahiru-no-Yo starts to become more aggressive, when Kuro kept on insulting Guren. She changes her attitude to the worse, wanting for Guren to make the boy suffer instead. Guren silences her but she reminds him she represents his own desires, and in return Guren states he can control her.

Mahiru-no-Yo doubts it, and wants proof saying to unsheathe her blade, Kuro as well demands for Guren to draw his sword. Mahiru-no-Yo continued as she urges Guren to speed things up, however she is ignored completely and without drawing his sword. confuses Mahiru-no-Yo. While Guren was in the middle of fighting the boy cleverly using traps, Mahiru-no-yo suddenly speaks gives a comment it isn't nice, but she is still ignored.

After beating the boy and is harshly talked to by Guren, Mahiru-no-Yo suddenly appears by his side, standing, commenting as well how good it would feel. She is delighted when Guren kept on scolding Kuro, and even reminding Guren that how he cleverly dispelled the boy's trap in the most painful way possible. Guren however knew she would love such moments reminding her of how she used to fool, toy and tempt with him and Kureto. Mahiru-no-Yo laughs at Guren, being clueless at girls opinions.

She says to Guren they've got an "onlookers enemies" watching them referring to his friends who were watching the whole fight. She suggest to Guren to give the audience what they want, and he silences her.

Guren then lectures Kuro about his actions, Mahiru-no-Yo says the reason he fought unsheathed is because he wanted to give a speech but is ignored by Guren. She keeps on going that Guren simply wanted to prove his righteousness, still ignored, but she goes on that Guren probably had some feelings to make it easier for him to punish himself as he was unable to protect them. This annoys Guren and shuts her up and go away, however she continues doing something like that isn't his fault which is probably what he wanted to hear. Guren gets more annoyed, and says for her to go away, returning his sword to his sheathe.

When Ferid confronted Guren in his apartment, Mahiru-no-Yo appeared behind Ferid, however he notices her presences, saying to kill him while he has the chance as he is an interference for their plan. She shouts at Guren to kill him, though Guren was yet unsure if he should kill him and listen to her. Interrupting his thoughts mentioning it should be obvious for Guren to only trust her and not resist her.

Not listening to her, Mahiru-no-yo sword flew to Guren's hands forcing him to kill Ferid. Guren warns Ferid that she is trying to kill him mentioning 'Mahiru' which he recognizes the name. He informs Ferid that the girl he knew is inside him, which amuses him, as she pressures on Guren to kill him, his body started to move according to her will which he is unable to stop it. Ferid laughs at what's happening, seeing as Mahiru has betrayed Guren despite them sharing a common enemy (Saitō).

As Guren sword started to move on it's own accord on to cut off Ferid's head, though he dodges. Guren started to feel weakened as his mind was consumed by the word to kill only, as a last resort he tells Mahiru to stop this. Mahiru-no-Yo then calms Guren, says to him to sleep as everything will be over when he wakes up. Knowing that she started to possess Guren, she declines so, as both of them are the same person and Guren sleeps.

Now a complete possessed Guren, Mahiru-no-Yo takes over his body, even changing his voice a little feminine. Ferid finds this all interesting, as he finally about to clash with Mahiru, simply saying that he will kill her, she talks to him how about Saitō feels about him, he is surprised that finally someone understands him, hating his father, though suddenly interrupted he is attacked by Guren, not even could Ferid counter the speed. The blade lunged straightforward twice as fast at his face, though Ferid managed to dodge it twice and attacks Guren, punching his face, away from his sword. As Ferid crushed Guren skull and he wonders why did Mahiru come out and possess him.

After his face heals, Mahiru answers to kill him, he wonders on who's orders, Mahiru could only laugh as it doesn't matter and she isn't capable of killing him, reminding him that he is in Shibuya, although it doesn't matter to him as they will find out who Guren is, if she would alert everyone to attack him.

Mahiru laughs as this has nothing to do with her, being Guren "pathetic" attachments. The sword then seemed to have a will on it's own as it struck the bed slicing it in half, cleaving on the wall even the walls. When the alarm made a sound that a vampire noble has infiltrated the barracks, As soldiers are gathering, Mahiru tells Ferid that this is the end for him as his confidence got the better of him. Warning him that today is his death, as they close on him but Ferid decides to run away and die another day.

Second Shibuya High School Arc
When a vampire escapes the school grounds, Guren uses Mahiru-no-Yo to slay it of which the power caused the vampire to disintegrate. Later when Kimizuki arrives in Guren's office and asks him if he can receive a demon weapon, Guren provides a demonstration of cursed gears power by showing him his demon aura as it fills his office. Later, Guren arrives at the classroom and unleashes Mahiru-no-Yo's demonic aura that sends most of the class tumbling to the floor, many of whom go unconscious without the willpower to withstand it. Shinoa manages to remain standing because of her immunity to all demons, and Yoichi is completely unaffected by the attack to the point where he does not even feel it. Yu and Kimizuki manage to withstand the demonic aura, though they tremble.

Shinjuku Arc
At the Shinjuku 5th Street intersection, Guren uses Mahiru-no-Yo to slay several vampires before confronting Mika and Ferid.

Post-Shinjuku Arc
Following a conversation with Shinoa, Guren meets with Mahiru-no-Yo in his mind. She wants him to seek more power. When Guren addresses her, Mahiru-no-Yo says she's glad that he came as she wanted to meet with him.

Guren challenges Yu to a fight to test him for the next step of mastering his demon, and in the fight, Guren orders Mahiru-no-Yo to possess him and overwhelms him.

Following their small talk, Guren reveals her form during a fight with Yu. After hearing Guren summon his demon by calling out her name, Shinoa holds her scythe at Guren's neck. She reveals that her weapon specializes in long-range combat and consequently stands no chance against a melee fighter like Guren at that range. Guren calmly says he would let Shinoa kill him. Shinoa asks him if that is his way to atone for killing her sister, unbeknownst to her that Mahiru stabbed herself by Guren's previous demon. Shinoa asks if she is in his sword since she heard him call her name. Guren says that Mahiru is already gone since she turned into a demon and saved the world by completing Cursed Gear.

Shinoa asks him if Mahiru is together with him inside his sword, stating that he is being possessed by her. Guren asks her if they ever got along. She explains that she was not close with her sister because Hīragis are raised without knowing familial love.

Shinoa asks if making use of Yu was one of Mahiru's orders and asks if her half-sister or the demon for lack of a better word inside his sword is ordering him. She then asks him to stop what he is doing if his goal does not benefit Yu.

Guren tells her that Mahiru is dead and isn't coming back. He says that the demon inside his sword is under control so he isn't being possessed by her. But Shinoa doesn't believe him.

Nagoya Arc
At the beginning of Nagoya, Mahiru-no-Yo appears and whispers to Guren in order to make sure he follows her rather than Lieutenant General Kureto Hīragi.

Mahiru-no-Yo later forms again, and possesses Guren and kills the noble, beating him. She uses Guren's body to point a sword at Krul Tepes and states that Krul will help her conduct an experiment on the Seraph of the End at Nagoya Airport.

At the Ebina rest stop Guren punishes Shinoa squad, in the fight against Yu Guren releases a powerful red whirlwind from his demon destroying the doors and knocking over Shinoa and Mitsuba. After the fight Shinoa charges at Guren only for her demon to get knocked off using Mahiru-no-Yo.

After defeating Mel Stefano, Guren moves to his next targets on his list Thirteenth Progenitor Crowley Eusford. Chess Belle and Horn Skuld. When Crowley was overpowering him he released Mahiru-no-Yo by in the ceiling by calling out it's name releasing dark crimson sparks. Guren eventually gets captured by the vampires after the fight with Crowley he was seen near Krul Tepes and a few of her soldiers. He was being beaten by a noble, the angered noble grabs Guren by the hair and raises up his face, when Guren spits on his face the vampire curses him and kicks him to the ground threatening to kill him.

At this point, Guren's personality begins to change as Mahiru-no-Yo possesses him and turned him into a namanari. With this power they easily behead the noble, with the sword appearing to have a will of it's own as it unsheathes itself. Guren's personality would change into more demonic and heartless though even in this state they could not defeat third progenitor Krul Tepes. Guren soon arrives at the airport in Nagoya where the experiments are being held by Kureto. Guren raises up his sword, and chains wrap around his arm as the curse consumes him speaking the words to drink the blood of human sacrifices, demons, and the progenitor turning Mahiru-no-Yo from black to complete pure red color similar to first-class vampire weapons. Guren then slaughters both vampires and a humans confusing everyone except Kureto,

After Yu stops the demon Abaddon, Guren still possessed by Mahiru-no-Yo, tells Yu to do it and break their taboos. As Guren chases Yu, Shinya stops him and asks him about betraying so many of his men before realizing Guren has been possessed.

Post-Nagoya Arc
After three months time skip Guren and Kureto can be seen walking and fighting together side by side against the vampires with their demon weapons. While so, both men commanded their respective demons to attack the enemies before them On his way back to Shinjuku, Guren injects the drug into his forearm while a soldier drives him. The drug suppresses his demon.

Osaka Arc
While Guren is driving away with the team, he reminisces back to eight years ago, when he triggered the Apocalypse by reviving his friends for the next ten years in order to be with them. Mahiru-no-Yo then manifests, and warns Guren that if his team ever learned that they are actually dead, they'll turn to dust. Once Guren tells her to disappear, she goes to the roof where she is then confronted by Byakkomaru. He demands for Mahiru-no-Yo to identify herself as she's not a demon; in response, she inquires him on what he would do about it. Byakkomaru replies that he would do nothing, unless she harmed Shinya. Mahiru threatens to kill Shinya if he knows about her, and harshly silences Byakkomaru. Guren tells her to leave, and Mahiru-no-Yo goes ahead of everyone to Osaka. She smells the scents of Shinoa and burning vampires which leads her to go investigate the latter scent. She appears right in front of an unsuspecting Ky Luc, before turning her attention to the burning crosses holding Ferid and Krul. Mahiru-no-Yo taunts a suffering Ferid, which caused him to notice her.

Despite Ky Luc being unable to see Mahiru-no-Yo, he gets an unsettling feeling, and tries slicing at it, but gives up. She then appears on the road that Guren and co are heading down. Upon seeing Mahiru-no-Yo waving to him, Guren tries unsuccessfully run her over. After arriving to Ferid's mansion, Guren summons her to knock out out the whole squad except for Shinya. She forms next to Guren, and comments that Byakkomaru is searching to kill to him. Guren says it's because she provoked him; as well as becoming annoyed with Mahiru-no-Yo before the fighting begins.

Seeing Guren and Shinya getting ready to battle, Mahiru says that this is the first time the two are fighting over her since high school. Guren denies this, and Mahiru-no-Yo continues by telling Guren she will sleep with whoever wins and claims it's his favorite scenario. Mahiru-no-Yo reappears after Guren's victory, watching over an unconscious Shinya before asking Guren why he brought his squad here; reminding him that they could be destroyed if they find out the truth. Though Guren doesn't answer her, Mahiru-no-Yo realizes that Guren is close to becoming a demon, thus he purposefully made his friends aware that he was hiding something to maintain his grip on his humanity. When Guren tells her to leave him alone, Mahiru-no-Yo reminds him that he has the power to banish her whenever he wants to. She later manifests in front of Shinoa, and expresses joy over seeing her alive and well, but then wonders why Shinoa is unable to see her. . Mahiru-no-Yo says that Shinoa should exceed her as an experiment before realizing that her demon has not awakened. She goes on to say that love, more specifically sexual desire and lust, will corrupt Shinoa until she no longer cares about the world. She stared at the gathering squad and noticed that Shinoa has her eyes set on Yu.

From him, Mahiru-no-Yo glances down to Shinoa, and sees that her younger half-sister is gazing at him. With that, Mahiru-no-Yo leaves telling Shinoa how much she is enjoying this.

After, she appears beside Shinoa when Guren is explaining the being that has been controlling the Hīragis and frowns when she sees Shinoa feel a pain in her chest.

Guren summons Mahiru-no-Yo to attack Ky Luc, and he recalls his uneasy feeling, having sensed her before.

Shibuya Arc
After the talk between Kureto and Guren, Kureto decides to attack him and Shinya. Guren summons Mahiru-no-Yo and manages to defend himself. She notices that Kureto has a great surge of power when he drew Raimeiki and when Shinoa comments this is bad, she agrees. Mahiru-no-Yo sees Shikama Doji floating behind Kureto and warns Guren that Kureto is being possessed by some unbelievably powerful monster.

Later on, Guren notices Mahiru-no-Yo manifests next to Shinoa after hearing Shinoa talks about how Shikama Dōji may have possessed her. She listens to Shinoa talking about how she gave up her life for to protect her from Shikama Doji with any hope of a relationship with Guren and Shinoa teases Guren that it is because of her that Mahiru-no-Yo never got to be together with Guren despite their love. After hearing Guren saying that the past doesn't matter that the catastrophe destroyed the world and how the past is gone and won't be back also what they should focus on the present situation and what they can do now, Mahiru-no-Yo complements Guren about his speech. Mahiru-no-Yo later sits next to her sister still manifested whom Shinoa can't see her.

When Guren and Kureto discuss how Shikama Doji went after Shinoa instead of Kureto since she is Mahiru's sister, Mahiru-no-Yo manifests and she listens to their conversation silently. She hovers nearby to Shinya and glances to frown at him since Guren knows he cannot let the dead realize they have been brought back to life or they will return to dust. Kureto suspects the monster went after Mahiru first and she makes no comment on that, or on speculation on why she approached Saito. However when Kureto asks Guren by whom or what is he possessed by and who is imprisoning him, Mahiru answers that the question is easy, that Guren is prisoner to love and friendship while embracing Shinya by the neck.

After the escape of Shinoa due to Saito's arrival, she manifests and tells Guren it won't be long before Saito and Krul arrive and it's time to betray everyone just as both of them planned, which Guren agree's on.

Mahiru-no-Yo continues urging Guren on betraying everyone even more assuring him it will only take a moment. They encourage Guren to let himself change to become the other Guren.

Mahiru-no-Yo contently asks Guren once more if he is ready to turn into a demon, and tells him she would give lots of encouragement when Guren alludes to declining. Saying that he is silly, Mahiru-no-Yo asks what he is going on about, failing is easier than succeeding since he could escape his responsibilities. Hugging him, they call Guren a crybaby and asks if he is scared. With the answer being in the affirmative, they ask since when. A flashback occurs when as Mahiru she first met Guren and was taken away from him.

Appearing concerned as they listen to Guren speak about how she had no one there to help her, and so no choice but to become a demon, Mahiru-no-Yo states that is not his fault. The catastrophe was going to happen, it was planned that way and if Guren had not done it, someone else would have. Trying to alleviate his guilt, Mahiru-no-Yo hugs Guren tightly and tells him it is both their fault, and now Guren is trying to take responsibility for it. They assure him it is okay, and not to worry, he will do it right and succeed. Seeing the chains emerge from Guren, she supports this telling him he is doing well and to keep it up, they will keep him safe. Mahiru-no-Yo intends to take half the demon into them, and will not allow Guren to go berserk

Noticing that Shinya and his squad have found Guren, she resumes persuading Guren to close his eyes and dive inside for Shinya, to save all of them. After some chains are shot, Mahiru-no-Yo makes eye contact with Shinya who can see them and is also perplexed at this fact. Mahiru-no-Yo reasons that it is because Guren is holding half the demon now. With Shinya's rifle aimed at them, they are demanded to say what is being done to Guren, but that is a secret. Holding Guren, Mahiru-no-Yo laughs off Shinya's declaration to kill them, telling him he does not have the power to do that. In response to Byakkomaru being called upon, Mahiru-no-Yo verbally activates the chains. With other squad members now able to perceive them, Mahiru-no-Yo has had enough of this nonsense and orders Guren to close his eyes. Once inside his mind Guren see's his sword thrown through Mahiru's chest who lays on the ground unconscious. Suddenly she screams in pain and Noya erupts out of her body.

Although separated into the two beings that make them up, Mahiru-no-Yo can be invoked as the singular being even though Mahiru is apart from Noya. The power emanating from the two bodies, combined with Guren as a demon and powered by chains were referred to as Mahiru-No-Yoru and were capable of combining their powers. Mahiru-no-Yo as a weapon is called upon by Guren and used to stab through Mirai to gain a sinful key. The sword is then used in the fight against the first who is possessing Shinoa's body.

With Mahiru then Noya returned to Guren's sword they could still be called upon individually but the cursed gear gave Guren greater power when they were within him. Whilst they could not see, they could sense the sheer mass of invisible swords that had surrounded Guren. Mahiru-no-Yo the sword was called upon to return and crush Yu's heart which it done by flying into his back.

Powers and Abilities

 * Demon's thrall: Mahiru-no-Yo may enter her host's mind and consume him with illusions in an attempt to break his will. If she wins, she gains control over his body.


 * Basic form: Mahiru-no-Yo appears as a black katana with a red streak down the middle. Merely drawing her increases her bearer's physical abilities significantly and calling upon her name increases them tremendously.038.jpg


 * Namanari: A human one step from becoming a demon. Mahiru-no-Yo has managed to turn Guren into one of these. In this form, Guren and Mahiru cooperate and have tremendous power. However, Guren's personality changes to a more demonic, heartless, and demanding one. It is unclear whether this is the demonic side of Guren that Mahiru began to create the summer before the Apocalypse when they were both human or if Mahiru is the one in control of Guren body.

Once Guren is possessed by Mahiru-no-yo, the blade would seem to have a mind of its own. The blade unsheathed itself from the scabbard and then proceeded to move around on air swiftly, beheading the noble vampire. In the manga, it was right after that did Mahiru appear as a ghostly apparition with mass-like demonic aura, hovering over Guren while his katana is equipped under her.

When Guren spoke of drinking the blood of human sacrifices, demons, and the progenitor, his katana drastically underwent a sudden change of color scheme. Through doing so, the katana itself went from being almost black in color to purely red of all blade length similar enough to vampire fire-class weapons used by the progenitors drank their blood. Not only that but something similar when Guren used a talisman to turn the color of a non-cursed gear's blade crimson from the light novel series, in the anime however he managed to turn his demon into completely from black to fully red without using or placing some talisman on it.

After merging with Noya, it should be noted that all Noya previous abilities are now in Mahiru-no-Yo, making her a very powerful demon.
 * Mahiru-no-Yo can also be used to devour an enemy's attack. If Guren was on the defensive side, he would then call on the demon blade's name to assist him in battle when he was knock far back and being sent flying to the ceiling. He will then used the demon's power and ability to cushion his physical impact for safe landing.
 * Mahiru-no-Yo can significantly increase Guren's physical abilities, and calling out her name would increase his power even more so. If Guren wishes to, he can invoke the demon's real name to have her possess him. This would cause Mahiru's apparition to appear and enshroud the blade and the arm wielding it with streaks of overwhelming flames, these flames are powerful enough to engulf an explosion in the midst of its vicinity, and even able to launch these flames at his opponent with one slash.

Additionally, Guren can utilize the power of the demon weapon for other miscellaneous purpose such as filling areas like the classroom with its immense demonic auras. Within the power's vicinity and range, victims pass out unconscious on the floor if they don't have the strength or willpower enough to overcome it. However, if the targets have high psychic resistance, used wards, or are a potential candidate for the Black Demon Series, they're not any bit fazed by Mahiru-no-yo's demonic aura. Merely drawing the katana from its sheath alone seeps blackish gases made from within in and out of the blade.


 * Anime: Guren would go on and further use the power of his demon weapon, Mahiru-no-Yo to summon forth a red whirlwind cloaked with thin layer of crimson-like demonic aura. More so, the demonic aura can be seen concentrating all around its inner layer and then being destructively launch at targets through him upfront within his range. This red whirlwind was able to demolish the concrete wall of a building, pushing even half Shinoa squad.

Equipment

 * Talismans: Even after becoming the demon Mahiru-no-Yo, she still use talismans and unique ones skillfully, such as a shikigami-shaped talisman, this kind of talisman allows her to dodge an attack if slashed, this is proved when she kept using them to overwhelm Mika, noted to be a powerful vampire. Her skills are so great that she can even place multiple ones for surprise attacks for her to switch her location between the talisman, if slashed the shikigami would be cut in half and she would be in different location, this technique is both defensive and offensive, it also prevents opponents from counterattacking. She also has exploding spell-tags using them with the same skill even prior becoming a demon, and as a demon.

Seraph of the End: Vampire Reign
"Demand it! Ask for it! Seek out more power!!"

- Mahiru-no-Yo to Guren.

"No, Guren. You won't. You'll follow me, right?"

- Mahiru-no-Yo to Guren when Kureto tries to lure Guren to his side.

"You always did have good friends, Guren. That's why it's imperative they don't find out. If the dead find out they've come back to life, they will turn back into the dust from whence they came."

- Mahiru-no-Yo to Guren.

"Aah... I can smell Shinoa's scent. She must be close. That... and I smell burning vampire... Aha ha! Someone is getting roasted like a side of beef."

- Mahiru-no-Yo about sensing her younger sister's presence, then to Krul and Ferid as they being exposed-tortured.

"Aah, this brings back memories of high school. Once again, my lover and my fiance are fighting each other over my hand..."

- Mahiru-no-Yo to Guren.

"What a peaceful sleeping face. Guren? Why did you bring Shinya and the others here? You had multiple other options. In fact, there was no need to act like you had secrets to hide in the first place. If they discover what happened, they'll vanish. That isn't a risk worth taking. So why did you do this? ...You've hit your limit, haven't you? Your heart can't take much more of this. If you didn't let your friends know that you were keeping secrets, that you were weak... then you'd become a full demon. That's why you told them. The drugs aren't enough anymore, are they? You must do things that go against your ideals... or you'll become a true demon—"

- Mahiru-no-Yo to Guren.

"You look well. I'm glad. But why can't you see me? You would make a far, far greater subject for this experiment than I ever was, after all. Your demon hasn't awoken yet, has it? Your greed must not be intense enough yet. You need to fall in love. A need for love. A need for physical intimacy. Let those desires grow and run wild, until you don't care the east bit about the rest of the world. So which one do you want? One of the boys, perhaps? Which one do you want to warm you at night? ....Aah... I love you so much, Shinoa."

- Mahiru-no-Yo to Shinoa while Shinoa cannot hear or see her.

Trivia

 * Her demon name Mahiru-no-Yo 「真昼ノ夜」 means "Midday's Night."
 * In the manga, Mahiru-no-Yo is the only one who could sense that Shinoa demon isn't awakened yet, and she requires love and lust which eventually happened.
 * According to the official Manga 8.5 Fanbook:
 * Interests/Likes: Guren's future, ambition, lust, the "Seraph of the End" experiment
 * Favorite food: Human hearts/minds, demons, cake
 * Crush: Guren


 * Though Mahiru-no-Yo is a demon, she retains all her memories in her previous life prior her death.
 * When she became separate from Noya, Guren turned into a namanari with him in control.