One Punch Across Ten Thousand Worlds

You transmigrate to a martial arts world where people are like wild grass, and life is at the mercy of fate. You choose to train in martial arts, so you go bald, but you get strong, too. You become the greatest under heaven, able to take on an entire nation alone. But being too strong is boring, so you choose to descend into a parallel world and fulfill another version of yourself's wish. The “good guy” Wang Yu brings warmth and a spring breeze to the Myriad Worlds... Whether anyone else believes it or not, he certainly does. (PS: The protagonist descends into multiple worlds as an invincible being. If you don't like the first volume, you can start from the second without affecting your reading.)