@Poyo-chan I can dig the reasoning having the knowledge and power, but having a younger body, kind of hinders the MC a bit logic. I remember an MC who got sent to another world, spending 5 years in it. He became powerful enough to slay a demon king and demon g**. But when he got sent back to Earth, he was back at the age of 5 years younger, but still retained his power from the other world. However, he couldn't unleash the power he used to defeat the demon king and demon g**, since he was in his highschool age of 15. Whenever he attempts to use his full power, he gets nose bleeds and pain all over his body. So when he faces threats on Earth, he relies more on wits and strategy, rather than brute forc