Saitama, the main character of the anime series One Punch Man is fed up with this this society of evil monsters always wreaking havoc to the cities. So he trains really really hard, to the point that his hair falls out, and obtains unimaginable strength! He joins this agency that recruits heroes, because he wants to be a just for fun and as well, to get money. He slowly climbs up the ranks, because he, from time and time again, single handedly defeats all of these incredibly strong monsters and soon gets recognized by the agency.