Yamisaka Ouma

Yamisaka Ouma (闇咲 逢魔) is a Japanese magician introduced in Toaru Majutsu no Index in Volume 5. He is adept in the use of a magical crossbow, which amplifies the power of his magic. He appears to capture Index in order to access a grimoire inside her that would allow him to save a woman who has been cursed to die.

Appearance
He is a tall man who is often seen wearing a black suit and tie. His eyes are always closed except when he is in pain or experiencing some other strong emotion. The Bow of Azusa is mounted on his right hand and acts as his main weapon.

Personality
He aims to use methods that would mitigate casualties and destruction. He fell in love with a girl who was cursed to die yet refused to cry out for help. He originally claims to act for his own ends, but that is only because he doesn't want to blame his actions on and shift his sins to her.

Background
Not much is known about him, though what is known is that he visited a hospital where he saw a girl with cursed markings on her body. Noticing him, the girl had a conversation with him, with her mistaking him for a funeral worker due to him wearing a black suit all the time. Ouma realized that the girl had accepted her fate, and remained resolute through her suffering.

Ouma then fell in love with the cursed girl, and tries to find a way to save her. However, he feels that he has to commit several sins in order to achieve that goal and that she would be the reason behind those actions; thus, he denies to himself that he is trying to save her.

Three Stories Arc
On August 31, Ouma appears during the afternoon searching for Index. Using his magical crossbow, he successfully manages to locate, and kidnap her while eluding Touma. He takes her to the roof of a building, and begins the ceremony of extracting Baopuzi, a Chinese grimoire that supposedly has a way to make someone immortal as well as a way to create a miracle drug that can cure any illness, the latter of which is his true goal in kidnapping Index. Predictably, the knowledge of the grimoire he is extracting from Index painfully deteriorates his body. Index pleads him to stop, though he disregards her warnings and continues on. In one instance, Ouma's memory regarding the cursed girl flows into Index, and Index tells him that his rationalizations for denying the reason behind extracting the grimoire are wrong, as he truly wanted to save the girl because he has fallen in love with her. Though because of the sins he committed, he doesn't want her to be the reason for committing the sins. Index once more pleads Ouma who is now squirming in pain to stop, as his death may cause even more suffering for that girl.

Touma (who overheard the conversation between Index and Ouma through his cellphone) arrives just in time to destroy the ceremony, and chastises Ouma for trying to sacrifice his life just so he can save the cursed girl's, as well as making it seem like he was the victim. Touma then offers Ouma a deal: he would dispel the curse on the girl’s body using his Imagine Breaker, which he explains to Ouma can negate any supernatural phenomenon. The two of them later leave Academy City together, with Touma apparently successful in dispelling the curse.

Kazakiri Hyouka Arc
Touma references Ouma as the one once again ties up Index and leaves her in their dorm due to the fact that she was making a fuss. Touma later notes on how Ouma helps break back into Academy City.

Abilities
Ouma mainly uses an Azusayumi (梓弓), a ritual instrument normally used in ceremonial dances by priests. The bow's purpose is not the shooting of arrows, but to use the pulling of the bow to cause sounds. It's is said that the impact can shake up demons. Originally, it was meant to be used to correct spiritual damage. Ouma's takes the form of a small bow mounted on a gauntlet on his right hand. Ouma can cast several spells by pulling the string of the bow to cause a sound. Additionally, Ouma has had his five physical senses enhanced (presumably through magic) to the point shutting down one or two senses won't hinder him, which is why he usually keeps his eyes closed.

Spells

 * Wind Demon's Bow String (風魔の弦): Ouma uses the bow to gather a large mass of air into a ball of wind the size of a beach ball near the ground. Since it's made of air, it's transparent and colorless, so it can't be seen with the naked eye. By stepping on it, Ouma can jump several meters into the air.
 * Piercing Bullet's Bow String (衝打の弦): Ouma uses his bow to shoot a transparent metal-like ball.
 * Seeking Demon's Bow String (捜魔の弦): The string of the bow resonates like a sonar, with the soft sound gradually becoming louder as it sweeps over the area to locate Ouma's target. Ouma was able to use this to scan the entirety of Academy City to locate Index.
 * Severing Demon's Bow String (断魔の弦): Ouma uses his bow to shoot several slicing wind blades. The blades of air aren't shot one at a time, they are released together gathered into something smilar to a mini-tornado.
 * Invisible Demon's Bow String (透魔の弦): Ouma uses his bow to turn himself and anyone he's carrying invisible.
 * Confusing Demon's Bow String (惑魔の弦): When leaving Academy City with Touma, Ouma used his bow to make the Anti-Skill officers at Academy City's gates think he had an exit permit. However, every person's mental barrier differs in strength, so the effects may differ.
 * Rope Binding Magic (縄縛術) is a magic technique, apparently based on (注連縄), which uses lengths of braided rice straw rope used for ritual purification in the Shinto religion. The technique is used to hold in bondage a person, it creates a magic boundary, and can be used to bind demons, and be used for torture. Due to its magical nature, it is susceptible to the Imagine Breaker, it is not certain whether the ropes were magical or the binding techniques.
 * Lantern Festival (盆踊り): By setting up a barrier that's mixes Shinto and Buddhism, he can amplify his bow's power to draw out Grimoires and read minds. However, this works both ways, so his target can read his mind as well.

Design evolution
Appearing only in a single volume, Ouma's design is static. According to Haimura, Ouma was originally a character for a Dengeki hp short story, this being the reason why he is not colored, and for the most part, the other character sketches introduced for the 5th novel volume.

Trivia

 * Though much of the Three Stories Arc is featured in Season 1 of the Toaru Majutsu no Index anime adaptation, Ouma's involvement in the story is omitted. However, both he and his story appear in the manga adaptation, as well as Season 2 of the anime adaptation.
 * He did not reveal his magician name.
 * He is one of the few people Touma has defeated in battle that has yet to reappear in the series.

Quotes

 * To Index: "There's nothing a magician can't do. I became a magician so that I'd never have to experience failure and frustration again!!"
 * In his memories: "Death is right in front of her, and yet she refuses to scream for help!!"
 * To himself: "But no matter how hopeless it seemed... I just couldn't give up on her."