Nagi Arisuin

Nagi Arisuin is a first year student from Hagun Academy and Shizuku's roommate.

Appearance
Nagi is a very effeminate looking man, having many effeminate features, like soft eyes, and very girlish lips, although this maybe 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 thing, even stating that it will some day 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.

History
Nagi comes from a small town in Eurasia, staying in a church with a nun and several children including his friend Yuuri. One day, his younger friends were kidnapped by a group of mob ordered by the mayor which resulted in the death of his best friend Yuuri. In rage, Nagi killed all the mobs emotionless but indirectly ended his friendships with his younger friends. While wandering alone, he ended up meeting Sir Wallenstein who offered Nagi a position in Rebellion which he accepted under the terms of being handed a large sum of money.

New Term, Reunion, and Rebellion
Nagi first appears inside his and Shizuku's room, alongside an angered Shizuku Kurogane over her issues with a certain princess who interrupted her and Ikki's moment together. Shizuku wonders if her love for her own brother was weird. Nagi then gives Shizuku some advice over this issue and decides to give Shizuku a makeover. Nagi is then invited by Shizuku, since her original plan was messed up by an intrusive Stella who invited herself along, wanting Nagi to be by her side, as she gains confidence when Nagi is around. Nagi and Shizuku, then meet Stella and Ikki outside the front gate of Hagun Academy, where he introduces himself to the latter, shocking them, as they assumed Nagi, being named Alice the entire time by Shizuku, was a girl. The group then heads to the mall, and visit restaurants while waiting for the movie to start. After finishing their lunch, Nagi follows Ikki to the bathroom, wanting to know Ikki a little bit better and starts a conversation with Ikki, realizing that Ikki is too used to being hurt to the point he can no longer hear the screaming of his soul in pain. Nagi sensing the surrounding then grabs Ikki and runs inside the bathroom as the sounds of shattering glass followed by guns and screams are heard.

Ikki contacts Kurono, who already knows the situation and tells them that Rebellion has hostages at the food court. Nagi uses his Shadow Walk ability to transports Ikki and himself to the top level of the mall staring at the hostages, and finding Stella and Shikuzu among them. Nagi then stops an angered Ikki, who was about to go down, showing him the message, that said Shizuku was putting up a barrier. The conflict subsides as Nagi points out to Ikki that Stella had taken care of the rest. Nagi then gets the cops to arrest the members of Rebellion.

Debut Battle and Vow
Nagi is said to have won his first selection match against an E-Rank within 10 seconds, although it was unknown what method he used. He then goes to Ikki's match and cheers him on as he fight Kirihara.

Impossible Victory, Decisive Battle, and New Beginnings
Two days after Ikki's impressive victory over Kuraudo Kurashiki, Nagi interrupts, Ikki and Stella's intimate moment, after they were finally able to be completely alone for once. He tells them that Shizuku's tenth round opponent had been decided. She will face the student council president Tohka Todo, who was in the Top 4 of the last years Festival.

Lorelei vs Raikiri
Shizuku loses her match against Tohka, despite showing an amazing amount of talent and skill. Nagi later comforts Shizuku in her hospital room, saying that she did great and that it's okay to cry and show bitterness over losing.

Siege, Reunion and Trap
Nagi was mentioned in having to fight in his own selection battle and was unable to go to Ikki's match against Tohka.

He had won his match as he was announced a participant in the 62nd Seven Stars Sword Art Festival by Kurono, but did not appear at the ceremony as he had to convey the information of the participants for Hagun Academy, to an unknown source who was a part of an underground group called Akatsuki, as well as revealing himself to being one of their members.

Training Camp and Scheme
Nagi is seen at the training camp, training for the Seven Stars Sword Art Festival which was happening soon, bringing along Shizuku who was on medical staff.

Nagi is later seen on the last night of the training camp stabbing Kagami in the back with his Darkness Hermit. When he contact Hiraga in order to tell him that Kagami had discovered their schemes. He asked if he should kill her, but Hiraga found that to be too complicated and instead insisted on hiding her, as their plan of attack would happen tomorrow morning anyways.

After Nagi had hidden Kagami's body, he went to his room where Shizuku was still awake reading a book. Nagi and Shizuku shares a drink together and Shizuku points out that Nagi had finally opened up to someone, as he hadn't done so since arriving at Hagun Academy, much to Nagi's own surprise. This brief conversation makes Nagi realize that Shizuku has become his dear friend, and he wants to protect her.

Akatsuki Strikes
While on the bus back to the school, with all the Hagun Academy participants of the training camp was on there, Nagi confesses to everyone that he was an assassin for Akatsuki Academy with the goal of stopping their movements and allowing the Akatsuki members to defeat them easily. The students had at first turned on Nagi after this revelation however, thanks to Shizuku pointing out the flaw of the very idea of an assassin pointing himself out before the plan is enacted, Ikki decided to trust them allowing the others to trust him as well. The students had arrived to a destroyed Hagun Academy, where they had faced off against Akatsuki Academy. Nagi was able to instead bind the students of Akatsuki with his ability, Shadow Bind. However he is soon stabbed multiple times in the back by Amane Shinomiya. It is then revealed that the real Akatsuki members were hiding as they knew of Nagi's betrayal thanks to Amane's ability. Nagi's unconscious body is then taken by Hiraga to Akatsuki Academy.

Nagi regains consciousness and is confronted by his master Wallenstein. Nagi tells Wallenstein that he betrayed him because he cared too much for Shizuku to allow her to be hurt. Wallenstein had become angered at such an answer and began to severely beat on Nagi. Shizuku then arrived and had battle Wallenstein and although she was unable to match him in power, Shizuku was able to outclass Wallenstein in technique and ability allowing her to beat Wallenstein and save Nagi's life.

After the Akatsuki scheme it is revealed that Nagi had dropped out of the seven sword art festival believing himself be a detriment to the team if he stayed in as a representative of Hagun Academy.

Dinner and Confrontation
Nagi, Shizuku and Ikki decide to go out to eat and are invited by none other then Yudai Moroboshi himself. They go to Yudai's family owned restaurant where Kiriko Yakushi, one of the representatives of the Seven Stars Sword Art Festival. After lunch Ikki separates himself from the group and Kiriko reveals why Ikki will have trouble overcoming Yudai.

Battle of Kings
Nagi and Shizuku, the next day, watch as Ikki goes on to fight last years champion Yudai Morobashi. Kiriko then comes by and explains that Ikki seems odd. Shizuku is then reminded of Yudai's tragic story along with his his sister's loss of voice.

Ikki and Yudai's match start and, although Yudai had the upper hand, Ikki is able to win, by using Edelweiss' own sword technique against him, allowing Ikki to move on to the next round of the Festival.

Conclusion of the First Match
After watching Stella's match against everyone in Block B, Nagi along with Ikki, Shizuku and Kiriko meet Amane Shinomiya. After Kiriko, who was supposed to fight against Amane is forced to withdraw due to her patients entering critical conditions, Ikki figures out Amane's ability to manipulate future events, called Nameless Glory.

Later Nagi and Ikki are relaxing in the bathhouse, they meet Byakuya Jougasaki, who was the runner-up of the last years Festival and Ikki's next opponent. Byakuya starts approaching Ikki and touching his body in amazement, with Nagi about to join, but Yudai shows up stopping Byakuya. Nagi and Ikki then leave, after Byakuya gives them cups of coffee.

The Warriors' Slightly Noisy Relaxation
Nagi, along with Ikki, Stella, Shizuku and the Akatsuki member Sara Bloodlily go shopping in the city. After the shopping Sara tells them about her past and connections with Rebellion.

A Fresh Bloody Truth
Shizuku tells Nagi about her plan to attack Amane, who is Shizuku's opponent in the quarter-finals, before the match. Nagi decides to help Shizuku, because she is his friend.

Nagi and Shizuku attack Amane, while he is in the waiting room. After Amane survives Shizuku's attack Nagi tries to use his Shadow Bind on Amane, but the lights of the room, temporarily go out, negating Nagi's shadow abilities. Amane then pierces Nagi with multiple swords taking him out of the fight. Amane also defeats Shizuku. Both Nagi and Shizuku survive and are later healed.

The Finals of the Seven Stars Sword Art Festival
Nagi, later watches the finals of the Festival, between Ikki and Stella, which Ikki wins.

After the Finals
Nagi later accompanies Shizuku to the hospital room of Ikki and Stella. Nagi quickly realizes that they have had, sex, and when Shizuku realizes this she attacks Stella.

The Festival is Over
Nagi participates in the party held after the Festival.

Abilities
Shadow Manipulation: Nagi's ability as a Blazer, Nagi can control shadows and use it to hide himself and his allies in it.

Expert Assassin: As a former assassin of Rebellion, Nagi is a skilled assassin, being trained by Wallenstein himself. This gained him the nickname "Black Assassin".

Device
Darkness Hermit (黒き隠者): Nagi's Device. It takes a form of a dagger and grants the user the ability to manipulate shadows. Nagi can materialize multiple Darkness Hermit for his Noble Art.
 * Shadow Bind (影縫い(シャドウバインド) Shadou Baindo): Nagi's Noble Art. By stabbing his Device into another person's shadow, Nagi can bind his target's movement. Once the target is captured, their movement is completely sealed and is impossible to break.
 * Shadow Walk (日陰道): A Noble Art, that lets Nagi travel through shadows. There is a limit to the distance that Nagi can travel with the technique, but within that limit Nagi can travel to any shadow he wishes to.
 * Hermit's House: A space inside of Nagi's shadows, that Nagi can enter anytime. He can also let other people in it. It's shaped like a small living room.

Trivia

 * Nagi refers himself as "a maiden born in a body of a man".
 * He's the second person Shizuku Kurogane opens up to besides her brother.