Tokyo Revengers

A middle-aged loser travels in time to his school years, and, in order to save the love of his life from future doom, he must become the leader of a dreaded school gang.
An unemployed man learns that his ex-girlfriend was murdered. He suddenly finds himself travelling through time to his middle school years and has chance to change the future and save the girl. He aims to rise to the top of the most brutal delinquent gang.