Tokyo Revengers

Tokyo Revengers is a manga written and illustrated by Wakui Ken.

Plot
Takemichi is a 26-year-old unemployed virgin who learns that the girl he dated in middle school, the only girl he ever dated, has died. Then, after an accident he finds himself in a time leap back to his middle school years. He vows to change the future and save the girl, and to do that he aims to rise to the top of the Kantou region's most brutal delinquent gang.