Namanari

Namanari 「生成, Half-Demon」 are humans who have two personalities in their body and are one step short from becoming full demons. They are extremely important in both the Guren Ichinose: Catastrophe at Sixteen and Vampire Reign series.

Becoming a Namanari
One can become a namanari by being infected with the demon's curse. This can happen by touching unrestrained cursed gear, such as with Guren Ichinose, or by removing the curses restricting the demon, as seen with Yūichirō Hyakuya in chapter 43.

Another way to become a namanari is to inherit the demon from a demon-possessed parent, which is shown in the cases of Mahiru Hīragi and Shinoa Hīragi. In this case, Mahiru saves Shinoa by devouring Shinoa's demon and maintaining two demons in her body. In exchange for saving Shinoa, Mahiru develops into a namanari much faster.

Development
The original human personality and the demon's personality gradually merge and form a new demonic personality. This demonic personality is a warped version of the original human personality. At first it is consumed by primordial urges, such as lust, destruction, and violence. Guren is embarrassed that he even gets turned on by blood. Eventually, this new wicked personality develops more complex and subtle desires. It becomes able to think of long-term plans instead of attacking everyone in sight, and can even hide its desires to the point where even close friends cannot tell that the demon is in control.

Even so, the original demon and new demonic personality remain separate. The new demonic personality is the warped form of the original human personality and will not necessarily make their shared body speak like the original demon and will not express the original demon's personal desires. The original demon may be separated from the host using a binding curse, such as what is used in cursed gear.

The first time the two merge appears to typically last a few hours. Guren first merges with Noya before 11 p.m. on August 21st, 2012. Noya begins to rest at about 1:40 a.m, the next morning, which leads to an estimation of roughly three hours. Mahiru commented that her demon possessed her much longer. Yu gets possessed for about three hours when he first merged with Asuramaru. After the merging, the demon goes to sleep for awhile. These two personalities will then fight for control more frequently and can switch out at any time.

Mika states that Yu spends an additional two minutes as a demon each day, and is worried that in half a year, the demon will nearly take control of Yu for nearly half the day.

A strong-willed namanari can resist their demonic side's influence for a period of time. However, when a namanari reaches puberty, the demon grows much stronger. Eventually the human side can no longer fight, and the person becomes a full demon. Guren notes early on that he cannot tell where his desires end and the demon's begin. Whenever the host becomes upset or consumed with desperate desire, the demonic personality takes over more easily.

Treatment
Guren uses an injectable drug to keep his demon half in check. He gives this drug to Ferid Bathory, who uses it on Yu to prevent him from becoming a full demon.

Possession
A simple demonic possession may happen at any time by a person who comes into contact with cursed gear and does not have the ability to overcome the demon. Since this may be a one-time occurrence, this simple possession may not turn the victim into a full-blown namanari.

When the demonic personality is in control of a namanari, it may also be referred to as a possession.

Personality
A namanari has two drastically different personalities. Depending on whether the human or demonic side is dominant at that moment determines the personality of that person at that time.

When their demonic side is dominant, they will be violent and cold to even their loved ones and are ruthless when it comes to achieving their goals. When the human side is dominant, they will typically adopt a more humane and gentle attitude.

Appearance
A namanari uses its host's body, so it appears like its host except for a few key differences. The presence of these distinct features confirms that the host is possessed or that the namanari personality is in charge. Note that the namanari may decide to appear identical to the host, despite being in control.
 * 1) The irises may turn red.
 * 2) The teeth may sharpen into fangs.
 * 3) The namanari may develop a horn or two.
 * 4) The sclera of the eyes may turn black.
 * 5) If a curse restriction is still in place, the curse marks will tattoo the host's skin.

Mahiru Hīragi (Later Mahiru-no-Yo)
The two Mahirus' appear identical but can be told apart by their drastically different behaviors. In the first Catastrophe cover, she had a red glint in her pupils, would often have fangs but no horns, and she tended to smile more vindictively in her demon form which contrasted with her kind and gentle human personality. Eventually the whites of her eyes become black more and more frequently.

Her human personality is often tearful and distressed, begging Guren to kill her while the demonic personality laughs gleefully as she taunts everyone around her and torments Guren. She is particularly cruel and manipulative, especially toward Guren and the girls who have crushes on him. Guren is able to bring the human Mahiru's personality forward for a short period of time.

Shinoa Hīragi
Not shown as Mahiru devours Shinoa's demon prior to Catastrophe in order to save her from becoming a namanari.

Guren Ichinose
When Guren is a namanari with Noya, he develops fangs, black sclera, and one horn. As a namanari, with Mahiru-no-Yo, the two Gurens appear identical. However, the namanari form heals all of the wounds the human version sustained and appears to be significantly more powerful. When the human Guren struggles against the namanari personality, curse marks appear on their body's face and neck.

The namanari form of Guren stands confident and proud. He no longer has a gentle expression and can kill his comrades at will without hesitation, despite the fact that his human personality would risk his life for them. His cruelty is startling. The first time he transforms, he slaughters everyone he sees and attempts to manipulate Mito into having sex with him, but the Imperial Demon Army eventually restrains him and uses curse restrictions to restrain Noya. Before this happens, he notices his demonic desires evolving. By the time of Vampire Reign, the demonic personality is mature enough to act and pretend to be the human personality, hiding his dark nature even from his closest friends, shocking Shinya with this revelation.

Note:  In the anime, Guren's wounds do not heal. He remains injured. He slicks back his hair, and his eyes turn red.

Yūichirō Hyakuya
Yu has red irises, two horns, and fangs when the demon is in control. When extremely distressed, his skin becomes tainted with curse marks and his sclera turn black.

The demonic Yu acts seductive or hateful and screams to be released from his confinement. It is unclear what he would do if he were released from confinement, but he screams about killing everyone surrounding him. He also tempts Mika with his blood and promises to run away with him, but Mika is not buying any of it. Since his friends are fully aware of what he is, they remain diligent about keeping Yu restrained while in this state. When he goes berserk, Mika is able to temporarily calm him down, but Yu fears he may even kill Mika in that state-of-mind.

Although Yu wants to save his friends and be with them, Asuramaru tells him his demonic self will kill everyone if it takes over Yu's body.