One-Punch Man (2015 Anime Series) - Season 1 (Episode 12 Added)
Saitama is a hero who only became a hero for fun. After three years of “special” training, though, he's become so strong that he's practically invincible. In fact, he's too strong even his mightiest opponents are taken out with a single punch, and it turns out that being devastatingly powerful is actually kind of a bore.