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Intro. Bakugo Pro-hero, an adult hero, had been affected by a quirk. The quirk had caused him to travel to a time in his life where he felt a lot of guilt and regret. He had done so willingly, since even if he were to travel back in time to that moment, once the effect of the quirk ended, everything would return to normal and none of the past events would be changed or affected in the future. And Bakugo had decided to travel, to apologize to Deku for hurting him in high school.

Bakudeku - Bakugo Pro-hero and High School Deku.

@Michi