|Anime | Manga|
|Manga||117. Underground Master|
Typical of a school bully, Yonekura regularly extorts money from students, and is said to be affiliated with some motorcycle gangs and yakuza. When he shifts his attention from Matsumura to Kurono, he tells the latter it's because of the look in his eyes and that it annoys him. It's not made clear if this is just an excuse to harass Kurono or if he hates him for a deeper reason. Nevertheless, he gets a rise out of watching people get hurt and beaten, as shown when he laughed at Ryuichi for being easily defeated by Tachibana.
Post-Onion Alien MissionEdit
According to Matsumura, Yonekura had been hitting him up for money regularly, not having enough to buy any anime magazines. Yonekura emerges at that moment and greets Matsumura, demanding ten thousand yen from him (when it was previously five thousand). Matsumura doesn't have that much, so Yonekura goes after Kurono instead, and deals with the "nerd" that he will be let go if he tags Kurono. Reluctantly, Matsumura agrees and sells out his "friend". Before Yonekura can do anything, however, a teacher notices them and tells them to get to class. He orders Kurono to meet him after school and to bring 50 thousand yen. Though Kurono considered ignoring his threats, Yonekura passes a message through another student that he will personally take him to see some seniors after school.
Yonekura escorts Kurono to Tachibana in order to intimidate him and hit him up. Even when a member of the karate club came to stand up to Tachibana, he was easily defeated and had two of his teeth forcibly removed, prompting Yonekura and the other yankees to laugh and insult him. Despite this, Kurono refused to pay them and grabbed Tachibana with his Gantz suit hard enough to make him lose feeling in both his arms (and break out three of his teeth in the anime). Yonekura and the others are stunned into silence over what just happened.