Mahiru-no-Yo

Mahiru-no-Yo「真昼ノ夜, lit. Midday's Night」is a possession-type demon of the Black Demon series which is Guren Ichinose lover former human, Mahiru Hīragi she is sealed within a sword and became Guren Cursed Gear.

Appearance
Mahiru-no-Yo appears exactly as Mahiru herself with the exception of having fangs and red eyes being a former vampire, she is the only demon who doesn't have pointed ears or horns unlike the others. She still wears her sailor fuku uniform of First Shibuya High School.

In her sword form she is colored as black katana have a glowing crimson, red streak that is outlined down in the middle portion.

Personality
Mahiru-no-Yo is Mahiru herself but since her humanity is gone and turned into a possession-type demon makes her particularly violent and the fact that she tells Guren to listen to her only but also helps Guren grow into a namanari and possesses him as needed to make Guren's demonic side take control.

However Mahiru doesn't appear to be as twisted when she herself became a namanari as she is able to keep calm and make rational decisions and unlike other demons who take desire from their host to gain more power, Mahiru doesn't use those methods, she also appears to still love Guren.

History
Mahiru-no-Yo was actually Guren previous demon, when Guren threw away Noya, Mahiru picked it up and stabbed herself with it in the heart and integrated with it, as Noya was unable to stop the curse from spreading, since Mahiru had planned this all along 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.

Second Shibuya High School Arc
When a vampire escape the school grounds Guren uses Mahiru-no-Yo to slay it. Later when Kimizuki arrives in Guren's office and asks him if he can receive a demon weapon, Guren intimidates him 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 those with willpower to withstand it. Shinoa manages to remain fine 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 manages to withstand the demonic aura, though they tremble.

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

Post-Shinjuku Arc
When Shinoa goes and meet Guren at the lab underground he mentions her sister Mahiru  invented Cursed Gear, and that sacrifices are necessary.

Following that, Guren meets with Mahiru in mind much to her happiness.

Guren challenges Yu to a fight to test him for the next step of mastering his demon, in the fight Guren orders Mahiru to possesses him and overwhelms him. After Shinoa heard Guren calling out his demon name, Guren calmly says he would let Shinoa kill him while holding her scythe at his neck. Shinoa asks him if that is his way to atone for killing her sister, unbeknownst to her that Mahiru stabbed herself by Guren previous demon. She 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 she and Mahiru ever got along. She asks if making use of Yu was one of Mahiru's orders and asks if her sister or the demon for lack of a better world that is inside his sword is ordering him, saying he is the one in control.

After discussing the events of 8 years ago, afterwards in she appears and whispers to Guren to only listen to her after talking with Kureto.

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 off 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 he goes on to his next target to 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 crimsion 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 personality began to change as Mahiru possess him and turned him into a namanari, easily beheads the noble, the sword seems to have a will of it's own as it unsheathed itself. Guren personality would change into more demonic and heartless. 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, 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 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 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. Mahiru goes ahead of everyone to Osaka. She smells the scent of Shinoa and burning vampires, which led her to go investigate the latter's scent. She appears right in front of an unsuspecting Ky Luc, before turning her attention to the burning crosses holding Ferid and Krul. Mahiru taunts a suffering Ferid, which caused him to notice her.

Despite Ky Luc being unable to see Mahiru-no-Yo, he had got an unsettling feeling, and tries slicing at it, but gives up. Mahiru later waves at Guren as he tries to run her over. After arriving to Ferid's mansion, Guren knocks out the whole squad except for Shinya, using Mahiru-no-Yo. 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 before the fighting begins.

Mahiru-no-yo appears in front of Guren after he won the battle, and he ignored her questions of bringing his squad. She realizes that Guren is nearing his complete transformation into a demon. When Guren tells her to leave him alone, she reminds him that he can do it whenever he wishes to. She later manifests in front of Shinoa, and expresses joy over seeing her alive and well, but wonders on why she couldn't see her. Mahiru became aware that her demon hasn't awakened yet, and 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. Mahiru departs saying how much she loves Shinoa.

Mahiru-no-Yo reappears beside Shinoa, and frowns at the sight of Shinoa feeling a pain in her chest, as Guren spoke about the being that's been controlling the Hīragis.

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

After the talk between Kureto and Guren, when Kureto decides to attack him and Shinya. Guren summons Mahiru-no-yo and manages to defend himself. Mahiru-no-yo see's Shikama Doji floating behind Kureto and warns Guren that Kureto is possessed by unbelievable powerful monster.

When Shinoa talks to Guren about how Shikama Doji went to her sister in the past and gave up her life and any relationship between her and Guren to save her from it, having hearing this she manifests and sits next to Shinoa in bed and complements Guren about his speech when he said the past is gone and never coming back and whats important is the present. She later sits next to Shinoa still manifested.

Forms 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

"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 Mahiru merged with Noya, it should be noted that all Noya previous abilities are now in Mahiru-no-Yo,                   making it a very powerful demon.
 * 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.038.jpg"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."
 * 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.
 * 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."