Evermillion

Evermillion (エヴァーミリオン), fully named White Princess Evermillion (白姫エヴァーミリオン), is an entity of unknown origin sealed inside Honoka Takamiya. She is addressed as the White Princess by various characters. A total of five seals were placed on her.

Appearance
Evermillion, when released from inside of Honoka, takes the appearance of an extremely tall, humanoid woman. Her ears are very odd, being long and pointed like those of an elf.

Her nails are also extremely long. In ancient history, in many cultures; this was a sign of great power. To have long nails like this, was a sign of the ability to have much spare time, meaning no work was performed by this person which might endanger his/her nails. Nails normally break, if used for their intended purpose, hence leisure and idle time.

She wears an extremely extravagant ballroom gown and has a small, cartoon-ish crown on her head.

Nearly every inch of her is white with a pinkish hue, including her hair, skin, and gown. The only exceptions are her red eyes and blue earrings.

Personality
Evermillion is very playful and easy-going. Even when facing off against Medusa she kept a very casual demeanor and then immediately engaged in a conversation with Honoka even as what little was left of Kazane Kagari's mansion was threatening to collapse.

She likes to tease others, such as calling Honoka "Honoka-kyun" and then claiming he had to give up his eyes to remove the petrification from Ayaka (though she was playfully fibbing).

She does have some concern for Honoka, saying he should avoid summoning her too often. One gets the feeling it is because, no resource is endless. She is probably concerned that too much of her may be drained too quickly to be of use, if she has to simultaneously fight the seals and produce power too often; her own existence might become at risk.

Background
Evermillion is a huge mystery. Her origins, how she came to be sealed in Honoka, why she was sealed, and even what she actually is; are mostly unknown (she referred to herself as a demon with Honoka, though it's possible she was being metaphorical). The Settings+Secrets notes in the third volume identify her as a witch. Sometime in the past she was sealed inside of Honoka Takamiya with a five layer barrier preventing her from escaping. She seems to have some history with Medusa.

(Warning: Minor plot spoilers ahead)

It is revealed through a flashback that Evermillion is a demon that was called forth by Honoka after Ayaka Kagari had been gravely injured when he was a child under Kazane Kagari's protection as her apprentice. She had tricked the young Honoka into forming a contract that allowed her to take possession of his body. However, he was able to subconsciously subjugate her and force her into a contract not unlike that of recruiting a familiar. This contract had also changed her appearance and personality, from that of a cold demon to the White Princess she appears to be now. She called herself "she who symbolizes destruction and rebirth: Evermillion" and agreed to resurrect the young Ayaka Kagari free of charge, stating "I'm really supposed to require equivalent compensation for this, you know, but we'll call it an introductory service!" She calls herself a demon of flames and asks Honoka to give Ayaka some of his mana* to her to jumpstart the resurrection process. She makes Ayaka a retainer to Honoka (explaining how and why she obtained the ability to take damage for him and negate damage done directly to her) and then disappears. How she was sealed inside of him and why are still currently unknown.


 * fun fact: This is actually a double entendre. The (mana) being used here refers to both the ordinary meaning of magical life force/power, but also literally means (kanji); the counterpart to (kana), as in kata(kana) and hiro(gana). So Evermillion, in the scene where she says this, is asking Honoka to use some of his life-force/power, and some of the kanji in his name.

The First Broken Seal: Takamiya-kun and Medusa and Evermillion Arc
Being surprised by Medusa's surprise attack on Babel, Ayaka ordered Honoka to go to the 12th floor, get inside her room, and close the elevator's gate. Ayaka transforms to her overdrive mode and fights Medusa, but she is defeated, and turned into stone. Just on that moment, Honoka who had managed to be wearing his robe, tries to grab Ayaka who was increasingly becoming petrified. When Ayaka became fully a stone, Honoka decide to eat the pill given by Chronoire, and summoned Evermillion...

Then Evermillion appeared, defeated Medusa with her Fire Craft. After that, Honoka asks her everything he had on his mind, and Evermillion asked him to be silent. Then Evermillion introduced herself and taught Honoka how to release Ayaka's curse. but in a playful fashion, Evermillion the White Witch; made it clear she wanted payment, asked Honoka to let her take a part of his body in exchange, and Honoka offered his eyes. The girl, seeing the purity of Honoka's intentions; said she was lying, and offered the advice Honoka needed. Then Honoka kissed Ayaka's cheek, while Evermillion was slowly disappearing as she had run out of time.

Medusa, recovering her strength again, this time flying with a pair of wings, she challenges the White Princess with the KMM Gang; but the now free Ayaka blows the gang down in an instance, and then managed to defeat Medusa.

The Second Broken Seal: Post-Takamiya-kun and Rinon-kun
A scheme to make the student council president popular, Honoka duels Rinon-kun in the gym,it is said Honoka presumably broke the second seal in that battle.

The Third Broken Seal: Post-Takamiya-kun VS Weekend Arc
The third seal was broken when Takamiya contracted Evermillion as a result of trying to save the lives of the people affected by a bomb magic,

Powers and Abilities

 * Even though she's sealed inside of Honoka Takamiya she was able to come out and save him from Medusa but only for a short time. It is assumed that the more seals are broken the longer she can stay free.


 * She uses a magic ability called Fire Craft (ファイアクラフト) that easily defeated Medusa and also destroyed Kazane Kagari's 41 story mansion as collateral damage. However, despite the power of her magic it didn't kill Medusa, it is assumed that since she still had seals on her, her power/magic was also confined/limited.
 * According to Settings+Secrets in Volume 3, Evermillion is capable of imparting her power to someone else in order to create a familiar. It's a very rare ability among witches.

Honoka Takamiya
She seems to trust Honoka Takamiya a lot but she told him not to depend on her too much.

Ayaka Kagari
Though being less in direct contact with Ayaka, Ayaka gathered the powers Evermillion emit though being sealed in Honoka's body to bring her overdrive modes.

Kazane Kagari
It is implied that the one strong enough to seal Evermillion is Kazane.

Medusa
It is unknown about the past Evermillion and Medusa has spent together, but Medusa seeks for her powers.