Maybe it's time(To let time pass through)

A harsh kick was delivered to his face. Tears welled up in his eyes that he dared not let spill. This. This was definitely real and not a dream. Somehow,he had traveled to the past and ended up back as a child in an unfortunate situation.

Or

Keigo is sent back in time and tries to fix everything. A plan fails and he says fuck everything, I'm becoming a vigilante.