One-Punch Man is an ongoing anime series that started in 2015. So far 24 episodes of One-Punch Man have been aired. One-Punch Man has no reported filler. 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.