Read Onepunch-Man (One) manga
Follows the life of a hero who manages to win all battles with only one punch. This ability seems to frustrate him as he no longer feels the thrill and adrenaline of fighting a tough battle, which leads to him questioning his past desire of being strong. MURATA Yuusuke of Eyeshield 21 fame approached ONE for a collaboration of talents, with his redrawn version of Onepunch-Man. Raw: http://galaxyheavyblow.web.fc2.com/ The translation started at chapter 31, because by the time it began, the redrawn version was already approaching chapter 31.