Eijirou Sharaku

Eijirou Sharaku (写楽 影次郎, Sharaku Eijirō) is a martial arts teacher at his family's dojo, Rakuei Gym, alongside his father, older brother Eiichirou, and younger sister Mikage. He teaches self-defense to Mairu Orihara and Akane Awakusu.

Appearance
Eijirou is shown most often as having short brown hair, a short beard, and wearing a grey tank top and shorts. He is not described in detail in the novels and was first seen when character sheets were released for the second season of the anime.

Adabashi Arc
While training Mairu, Eijirou warns her to stay away from Kisuke Adabashi, a man who has been coming to the dojo lately and whom Eijirou feels is dangerous. At Mairu's invitation, he soon after joins the chat room.

Amphisbaena Arc
Eijirou and Izaya fight outside the dojo until Mikage overhears them and puts a stop to it. Mikage berates and severely beats Eijirou for disgracing the name of their gym by starting a fight in public, as well as implying she was raped to everyone within a three block radius. Mikage lets Izaya escape and is about to leave when Eijirou stops her again. He asks if she is still interested in Izaya after all that he has done, and she knocks him out in response.

Final Curtain Arc
Eijirou, Egor, and Shingen save Namie Yagiri from Seitarou Yagiri and Kasane Kujiragi.

Izaya Orihara
Eijirou despises Izaya with a passion. His hatred for the info broker comes from the fact that Izaya took advantage of his sister (who had a crush on him at the time, as Eijirou was aware of) when they were teens, and he manipulated her into the taking the fall for a scandal that made her drop out of high school. The incident forced her to take up the family business as she had no real options for work and, as Eijirou claims, ruined her life. When he sees Izaya talking to the twins, he immediately attacks.

Trivia

 * We can see a poster of Eijirou in Durarara!!x2 Ten episode 4 at Russia Sushi.
 * The name Eijirou means "shadow, shade, other side" (影, ei), "next" (次, ji) and "son" (郎, rou).
 * The surname Sharaku means "copy, photo/be photographed, describe" (写, sha) and "easy/ease, comfort, music" (楽, raku).