Cry Baby

Keito Kazuto, one of the founding members of the Tokyo Manji gang and the first man who had Mikey's respect, while he was younger than them, situations had to make him an adult early in his life, and because of this he was seen as a big brother to his friends from his adult way of thinking, even though he was younger than them.

But an incident befall upon Toman that started their metamorphosis into a savage, ruthless, and a merciless gang which made Kazuto abandon the gang, with guilt and regret knowing he could've prevent this transformation happening.

(A Tokyo Revengers story from another timeline where the main character remembers everything after a time leap, but is not a time leaper himself. Everything except my OC is not owned by me.)