Mahiru-no-Yo is a being that came into existence when Mahiru Hīragi stabbed herself with a Cursed Gear blade with the demon Noya within it. Fused together as a result to become one entity, Mahiru-no-Yo would not benefit from two sets of distinct interactions that would be expected from a human girl turned vampire, and a black demon. Rather the opposite, being invisible to all as a demon themselves, it would also not help in creating connections where Mahiru-no-Yo would express a great deal of interest in possessing her host Guren Ichinose.
Indifferent to the Hīragi Family feuds that factored into Mahiru's decisions, in the rare case of seeing other powerful supernatural beings such as vampires and other demons such as Byakkomaru, they would pay them little mind. Nevertheless, Mahiru-no-Yo is dependable in providing power when Guren calls for it against such foes. Being cursed gear, they would be regarded, if at all, as just a sword.
Systematically, it is on Mahiru's side that the demon acts on in reminding Guren to progress ongoing plans. Where they would posses him, through Guren's actions Mahiru-no-Yo would significantly shape major events. Mahiru-no-Yo interacts with few other characters throughout the Seraph of the End series, which barely affects themselves, yet heavily influences the story. This article details Mahiru-no-Yo's relationships with other characters.
Japanese Imperial Demon Army
A weapon used by Guren who acts on orders from the Japanese Imperial Demon Army, Mahiru-no-Yo would be used to carry out their directives. While having memories of Mahiru's Hiragi family members that manage the army, Mahiru-no-Yo would display little interest in their current positions, only speaking if some of their orders could come into conflict with their own.
Also involved with the Moon Demon Company, a branch organization under the Japanese Imperial Demon Army, similarly they would be acquainted with Guren's friends from when Mahiru knew them. While it may have come from a place of consideration, it is equally likely that Mahiru-no-Yo would express concern for others as a manipulation tactic to encourage Guren to see them as someone who has his best interests at heart.
|“||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.||”|
–Praising Guren's friends and reminding him of the perils of certain knowledge. Chapter 54: "Sinner's Christmas"
Nevertheless, if they could, Mahiru-no-Yo did not reveal details that could have resulted in Guren's friend's demise, which very likely would have tipped him over the edge where he would be further susceptible to possession.
A relationship largely of Mahiru-no-Yo being a weapon for Guren to use, while also on standby to prod him in the direction of their path. Where Mahiru was romantically attracted to Guren Ichinose before becoming his sword, Mahiru-no-Yo seemingly harbors a different kind of affection. Treated coldly by Guren, they are often ordered to be silent, or outright ignored when Mahiru-no-Yo attempts to speak with him. Granted, it is on account of Mahiru-no-Yo being a demon actively working to posses him, yet they apparently do not consider what it must be like for them to have the appearance of the girl that Guren liked, yet is an uncaring literal demon within.
At first, Mahiru-no-Yo was believed by Guren to be nothing but a fantasy created by Noya, until it was found out that they represent his desires. Mahiru-no-Yo does not seem to register, or care, that they were seen as a hallucination, then as a demon taunting Guren for possession purposes. While on the surface it seems that Mahiru-no-Yo has retained her love for Guren, such as being delighted whenever they are spoken to in his mind, in true demon sense, it seems a ploy to entrap him with varying degrees of success. In some cases Mahiru-no-Yo would be spoken to intentionally, just to pass some time or for information they could provide.
Although not above taking control at times, such as in attempting to destroy threats to their plans such as Ferid, they mostly allowed Guren to do whatever he does. They manifest quite often when Guren mentions Mahiru or Shinoa, much to their happiness. While Mahiru-no-Yo sometimes complements Guren, they go as far as to comfort him in his demonic form. Willingly shouldering the blame of causing the Catastrophe along with him, and offering a hug, Mahiru-no-Yo eases Guren to accept his demon side, and would draw upon considerable power to repel others who interfered with that ultimate goal.
Mahiru's younger sister, their invoked name is heard by Shinoa Hīragi when she hears Guren speak it. Not commenting on Shinoa there, Mahiru-no-Yo may have heard the concern that Mahiru is possessing Guren. Neither is there any response when Shinoa feels anger at her sister being within Guren's sword, where she is convinced he killed Mahiru. Similarly, nothing is said such as correcting this assumption, as in actuality Mahiru stabbed herself and was fused with another being. Of course, it is possible Mahiru-no-Yo was in control of Guren at the time and was giving assurances he was not possessed in an attempt to direct attention away from what could have been the reality they did not want to discuss. They were also active at the battle of Shinjuku, yet where Shinoa's life was in danger from vampires, and Yūichirō Hyakuya as a partial seraph, there was no action taken. True to being a weapon, Mahiru-no-Yo remained idle, with only calls for the sword's power being present.
When manifested outside the weapon, Mahiru-no-Yo expressed familiarity at Shinoa where they did not before. Seeing Shinoa, they set about analysing the potential for her demon to awaken.
|“||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.||”|
–Speaking to Shinoa who cannot hear or see her. Chapter 56: "Loose-Lipped Vampire"
Not so much forlorn, Mahiru-no-Yo perhaps expected with her demon active that Shinoa would be able to perceive them. For Shikama Dōji within her, Mahiru-no-Yo alone would correctly predict that Shinoa's love related feelings would allow him to become active. Continuing to speak forthrightly despite unable to be heard, it can only be guessed whether the love professed for her sister was genuine, or was in regards to her potential for demon possession herself.
Where Shinya was Mahiru's fiance, Mahiru-no-Yo makes reference to that, however her behaviour to him is firmly in the realm of seeing him as Guren's friend who he wants to protect. It is Shinya who Mahiru-no-Yo places their arms around when speaking to Guren of how he cares for his friends.
A possession-type demon, Mahiru-no-Yo operates by consuming human desires to create power for her host. Resulting in a human benefitting from greatly enhanced physical capabilities, Mahiru-no-Yo does not need to materialize where the human will be doing all the fighting, but can do so, usually when providing a greater degree of power.
Unique among demons, Mahiru-no-Yo is a merged being of a vampire, and a black demon. Together they inhabit a Cursed Gear katana sword. While seemingly a rare encounter, Mahiru-no-Yo does not dwell on coming across other demons. Although Noya knew some in the past, it would make sense if Mahiru-no-Yo has no memories pertaining to demons. They are however very keen to turn Guren into a demon like them.
Guren's previous demon, Mahiru was the one who gave Noya to him. Stabbing herself to fuse with Noya, she paid little attention to his fading voice when they together became Guren's demon. Some time later, Mahiru-no-Yo would apparently experience pain when Noya began erupting from their body. Revealed that he did not completely disappear after he was merged with Mahiru, it seems when active Mahiru-no-Yo had the typical demonic inclinations, though tempered ones. If Mahiru-No-Yo is separated into Mahiru, and Noya, it appears to factor into Guren being able to change into a namanari, but with himself in control.
A white tiger based demon, Byakkomaru resides within Shinya Hīragi's cursed gear rifle. Apparently sensing him, then floating up to the roof to interact, Mahiru-no-Yo's first meeting with Byakkomaru took place when Guren's Squad was heading to Osaka, Finding his tiger form manifested in front of them, Mahiru-no-Yo makes no comment on his cautiousness of them, neither the remark that he can tell they are not a demon. In the response to the threat that if they try to harm Shinya, they silence him where Mahiru-no-Yo ignores the warning. Although the demon of Guren's close friend, Mahiru likely thinks lowly of Byakkomaru if addressing him as a beast in a derogatory manner is anything to go by.
The demon within Yu's sword, Asuramaru is not referred to even as Guren clashes against them using the Mahiru-no-Yo weapon. Significant because it is another black demon, and then Ashera, who became Asuramaru and his whereabouts are critical in Mahiru's bargain with his sister, Krul.
The first vampire, Shikama Dōji was behind the creation of the species that could be turned into demons. Able to perceive him, Mahiru-no-Yo warns of his power.
Where Mahiru was a vampire, one turned by third progenitor Krul Tepes, in becoming a cursed gear, Mahiru-no-Yo would be used extensively in the campaigns against the blood draining captors of humanity. Unlike humans, where Mahiru-no-Yo has memories of them, when it comes to vampires in particular there is no familiarity shown at all. It is plausible that Mahiru-no-Yo's memories of them had been erased entirely. Not expressing an opinion on vampires, Mahiru-no-Yo the weapon complied with Guren's actions of providing the means to defeat these supernaturally powerful beings.
The leader of the Hyakuya Sect, Saitō is a former second progenitor vampire. Prior to becoming Guren's Cursed Gear, Mahiru worked together with Saito in the Hyakuya Sect. While Mahiru worked closely with him, and it stands to reason that Noya would have been aware of Saito from the past, Mahiru-no-Yo seem to have no memory of him after becoming Guren's sword. However, Mahiru-no-Yo is known by Saitō, namely why Mahiru became a demon. Furthermore, Mahiru-no-Yo has a sinful key thrown into their neck, which according to him he hid a sin.
Where Mahiru made an almost world shaping bargain with Krul, a third progenitor, and the queen of Japan, concerning the whereabouts of her brother Ashera, and was turned into a vampire by her, strikingly Mahiru-no-Yo makes no mention of this. Even when it would have been in their, and Guren's interest when he was captured and interrogated by her. Not even hinting if they remember it, Mahiru-no-Yo empowers Guren as a namanari in Krul's presence, only to still be swiftly pushed back. Silent as Guren does all the talking, it would have been helpful for Mahiru-no-Yo to reveal the bargain was still upheld, and ongoing.
Similarly, Mahiru-no-Yo shows no familiarity with Krul when treading close to where the deposed queen was. From the visit, Mahiru-no-Yo saw that Krul was being guarded by Ky Luc. Both in sword and spirit, Mahiru-no-Yo would take part in the effort to free her from the sunlight exposure torture she was experiencing, though all at Guren's direction and not out of an apparent intent to assist Krul due to being familiar with her.
A seventh progenitor vampire, Ferid Bathory has been working with Mahiru for quite sometime. However, upon becoming Cursed Gear, Mahiru-no-Yo had an instinct that Ferid would approach Guren and use him. Accordingly, Mahiru-no-Yo ordered Guren to kill Ferid, and they are not above possessing him to help achieve this aim. Regarding Ferid as someone who gets in Guren's way, the wider issue is Mahiru-no-Yo feels they should be the only one who Guren should listen to.
Finding Ky Luc, a fifth progenitor monitoring the sun exposure torture that Krul and Ferid are weathering, Mahiru-no-Yo assesses that he is right that there might be a ghost. Whilst they cannot be seen, something about them can be detected on some level by Ky Luc. Identifying that he was there, Mahiru-no-Yo appeared in the road before Guren which caused him to change his path from where Krul and Ferid were, and instead travel to Ferid's manor where Shinoa squad was situated. In later attacking Ky Luc, they were summoned and in materializing, Mahiru-no-Yo joined the attempt to kill him.
Engaging this reported thirteenth progenitor as a sword, Mahiru-no-Yo would be relied on for Guren to buy time for hostages to be rescued at Nagoya city hall. The weapon was invoked to emit a darkness that allowed Guren with Shinya to escape from the vastly stronger noble. They did not come to assistance when Guren was captured by Crowley, where it is possible Mahiru-no-Yo communed with Guren at some point as this was his plan to be taken hostage. While they would be around one another at Ferid's mansion, Mahiru-no-Yo makes no comment on Crowley, yet as a sword they would not be used to battle him again.
Where Mahiru had an interest in Mika, with Noya even acknowledging his existence, Mahiru-no-Yo as a weapon would be used in a battle against him in Shinjuku. Apparently no word was given to Guren on his importance to their forerunner's larger plans. It is not likely that Mahiru-no-Yo would have restricted Guren's fighting capabilities. When Guren was stabbed by Mika, the lack of action from Mahiru-no-Yo is in keeping with inactivity when Guren is in similar dire circumstances. Firmly a weapon whose capabilities are dependent on Guren in this situation, one among many, it is also probable that Mahiru-no-Yo had forgotten who Mika was if they even differentiated him from any other foe that Guren was up against.