One punch man

On an Earth plagued by terrifying monsters and villains, Saitama is an uniquely powerful hero who can defeat any opponent with a single punch. However, after undergoing three years of intense physical training to achieve this level of power, Saitama's invincibility has left him completely bored, as no opponent can challenge him in a real battle. Along with his loyal cyborg disciple, Genos, Saitama joins the Hero Association to seek official hero registration, defend humanity, and search for a worthy fight.