HOLY I thought this was gonna be a bit cringe based off the cover but OMG the plot twits are great! This kinda reminds me of Tokyo Revengers, sadly this hasn't updated since 2021, pity :(
Yang Do-hoon was living the happiest moment in his life. One day, he is murdered by an unknown person without knowing the reason and returns to his high school days. Do-hoon, who inferred the criminal in order to change the future, doubts Han Young-un of the same class.