Yokosuka

Yokosuka (横須賀) is a minor character in Toaru Majutsu no Index. A member of Skill-Out, he is a self-proclaimed anti-esper battle expert involved with Dark Side of Academy City.

Appearance
He is described as a "huge muscular human" and is probably like Komaba Ritoku in build.

Personality
Apparently confident enough to take on a Level 5 esper, he is also quite tenacious, not allowing Gunha to beat him after a few attacks from his "Amazing Punch". Despite this, he is still a Skill-Out, willing to beat defenseless people for money.

Background
He's a leader of a Skill-Out group near a shopping district in Academy City. He addresses himself as Yokosuka The Organ Crusher (内臓潰しの横須賀).

The Third Friday of March
On March 15, 8:10 PM, the day after White Day, in the current year of the story timeline, his subordinates come upon Haratani Yabumi and drag him into a back-alley near the shopping district to mug him. Yokosuka doesn't participate in this but observes their actions in the sidelines, and later find the arrival of Sogiita Gunha, the seventh of the seven Level 5s.

After Gunha easily defeats his men, Yokosuka arrives and threatens Gunha for sticking his nose where it doesn’t belong, and says that he is an anti-esper battle. Before he can finish, Gunha farts, much to Yokosuka’s irritation. After remembering what he was trying to say, Yokosuka continues to threaten Gunha. However, before he can finish, Gunha once again interrupts and shouts Amazing Punch at him. As he protests his rudeness, the punch connects despite being more than 10 meters away from him. Still conscious, Yokosuka asks what Gunha did, to which Gunha replies that what he did was the true worth of him being the 7th-ranked level 5. He explains to him that he can create an unstable wall of psychokinesis in from of him and destroy it with a stimulus provided by his own fist, which then causes it to send an explosive after-effect from a long distance. He then says that he calls his ability Attack Crash.

Hearing all this, Yabumi finally speaks up, saying that what Gunha said is impossible. He tells him that applying a stimulus to a field of psychokinetic power shouldn’t have that kind of reaction. He tells Gunha that his chosen field of study is psychokinesis and backs up his claim by saying that he is chosen field of study is in psychokinesis. Both Gunha and Yokosuka are silenced by Yabumi’s claims. However, Gunha then lowers his gaze and clenched his fist, asking what he did and how he did it. Yokosuka says that what he is currently doing is a half-assed way of treating his special move, and that he should think about the people who were taken out by it feels. Yokosuka then complains but is silenced by Gunha using Amazing punch on him again, making him fly into the air.

Seeing this, Yabumi cannot feel happy about being saved. Yokosuka tries to stand up again to Gunha but his legs were shaking, though impressed by Gunha. Although Yokusukua doesn’t have the strength left to fight or even run away, he looks up to Gunha’s face and asks him, with a smile, that Gunha should at least finish the fight with some extraordinary attack unlike the boring sounding Amazing Punch, something that can be worth losing to. Despite this, Gunha just uses Amazing Punch on him again.

St. Germain Arc
Yokosuka's encounter with Gunha made an impression on him. Wanting a way to deal with Gunha, Yokosuka starts working for Aihana Etsu, the 6th-ranked level 5. He however gets roped into Etsu's plans of helping people solve their problems by allowing them to use his name as the 6th-ranked level 5. In spite of that however Yokosuka still gets paid 700 yen an hour for his troubles.

It is Yokosuka who beats up Kanou Shinka for snooping in the business of the Dark Side of Academy City and the same one who suggests to him to use the name of Aihana Etsu,

Toaru Jihanki no Fanfare
It is revealed here that he has developed a certain level of rivalry with Gunha, displaying enough persistence to challenge him 30 times; he has also developed his physical resistance to the point were he can take 10 Amazing Punches before being defeated.

Quotes

 * (From NT Index volume 12): "Welcome to the underside of the world, ‘Aihana Etsu’ #...oh, I’ve lost count."