Nagi Arisuin

"I met Shizuku, and I finally remembered. What kind of adult I wanted to be. The desire that I myself tried to run away from, to rebel against, to throw away…"

- Nagi Arisuin

Nagi Arisuin came from an orphanage in Eurasia with her best friend Yuuri who soon died after both their government officials and mayor hired a gang to "clean up" their streets. She saved all the children from the orphanage after killing the gang, but all the kids soon became afraid of her. Nagi joined Rebellion under the teaching of Wallenstein after both killing the mayor and sending money to the orphanage.

Nagi became known as the Black Assassin and was later sent to Hagun Academy as a first-year for the upcoming 62nd Seven Stars Sword Art Festival as one of the students of Akatsuki. She became the roommate of Shizuku, then befriended her brother and Stella causing her eventual betrayal.

Appearance
Nagi is a very effeminate looking man, having many effeminate features, like soft eyes, and very girlish lips, although this may be due to the fact that she believes she is a girl trapped inside a man's body. She has very long dark hair, that covers most of her forehead, and goes down all the way her ears.

She is usually seen wearing her Hagun academy school uniform as well. He also wears a religious cross, tied in with a necklace, around her neck.

Personality
Nagi is a very kind-hearted person who cares for her roommate Shizuku, constantly encouraging her and supporting her love towards her own older brother Ikki. She also seems to be very analytical, more so than she is leading on, as she analyzed Ikki and told her that Ikki's strength and her pain tolerance were the same things, even stating that it will someday destroy her.

The kind-hearted person, however, was shown to be just a persona of her, to trick the other students into believing that she was harmless when in actuality she is very cruel and doesn't even care about her supposed friend Shizuku, stating that she will still be done in.

Eventually, Nagi started to really care about Shizuku and the others as real friends, this would cause Nagi to betray Akatsuki and Rebellion.

Abilities
Shadow Manipulation: Nagi's ability as a Blazer. She is able to manipulate the concept of "Shadows" letting her control surrounding shadows in the area ranging from her allies and enemies. As such, Nagi can also hide himself and her allies in shadows, as well as travel through them.

Master Assassin: As a former assassin of Rebellion, Nagi is a skilled assassin, being trained by Wallenstein himself. This gained her the nickname "Black Assassin". Nagi also possesses great skill in deceiving her targets, making them trust her, before stabbing them in the back.

Expert Combatant: Nagi is a skilled fighter, having defeated numerous opponents in the Hagun selection battles. Even as a child, Nagi was able to kill multiple adult men, ripping their bodies apart.

Device
Darkness Hermit: Nagi's device, which takes form as a unique-shaped jagged black dagger. Darkness Hermits acts as a medium for most of her noble arts and materialize copies to use in combat and maximize her noble art.
 * Shadow Bind: Her first Noble Art, where she stabs her Darkness Hermit in another person's shadow, letting her bind their movements leaving immobilized. This has proven to be nearly impossible to break unless Shadow Hermit is removed from their shadow.
 * Shadow Walk: Her second Noble Art, where Nagi travels through shadows. In spite of the limit in the distance that she can travel using Shadow Walk, Nagi can travel through any shadows she wishes to without limit.
 * Shadow Spot: Her third Noble Art, where Nagi creates a hidden room that exists in the space in between shadows, which she can enter anytime she wishes and can also let others in. Shadow Spot takes form as a small living room that has gas and water.
 * Shadow Beast: Her fourth Noble Art, where Nagi summons different kinds of creatures from pools of shadows. And so far, she has shown to be able to summon shadow tigers and bears.

Trivia

 * Her first name (凪) means "Calm" and "Lull".
 * Her surname (有栖院) means "Peculiar Temple".
 * Although, Nagi is a man at birth, she refers to herself as a "maiden in the body of a man", which is commonly used to identify someone as transgender.
 * She's the second person Shizuku Kurogane opens up to besides her brother.
 * Nagi is very knowledgeable about fashion.