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 his best friend Yuuri who soon died after both their government officials and mayor hired a gang to "clean up" their streets. He saved all the children from the orphanage after killing the gang, but all the kids soon became afraid of him. 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. He became the roommate of Shizuku, then befriended her brother and Stella causing his 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 he believes he is a girl trapped inside a man's body. He has very long dark hair, that covers most of his forehead, and goes down all the way his ears.

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

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

The kind-hearted person, however, was shown to be just a persona of his, to trick the other students into believing that he was harmless when in actuality he is very cruel and doesn't even care about his 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. He is able to manipulate the concept of "Shadows" letting him control surrounding shadows in the area ranging from his allies and enemies. As such, Nagi can also hide himself and his 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 him the nickname "Black Assassin". Nagi also possesses great skill in deceiving his targets, making them trust him, 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 his noble arts and materialize copies to use in combat and maximize his noble art.
 * Shadow Bind: His first Noble Art, where he stabs his Darkness Hermit in another person's shadow, letting him bind their movements leaving immobilized. This has proven to be nearly impossible to break unless Shadow Hermit is removed from their shadow.
 * Shadow Walk: His second Noble Art, where Nagi travels through shadows. In spite of the limit in the distance that he can travel using Shadow Walk, Nagi can travel through any shadows he wishes to without limit.
 * Shadow Spot: His third Noble Art, where Nagi creates a hidden room that exists in the space in between shadows, which he can enter anytime he wishes and can also let others in. Shadow Spot takes form as a small living room that has gas and water.
 * Shadow Beast: His fourth Noble Art, where Nagi summons different kinds of creatures from pools of shadows. And so far, he has shown to be able to summon shadow tigers and bears.

Trivia

 * His first name (凪) means "Calm" and "Lull".
 * His surname (有栖院) means "Peculiar Temple".
 * Nagi refers to himself as "a maiden born in the body of a man".
 * He's the second person Shizuku Kurogane opens up to besides her brother.
 * Nagi is very knowledgeable about fashion.