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.
To escape the police, a father and his son are forced to find refuge in a summer camp for young adults with mental disabilities, taking on the role of an educator and a boarder.
In Orario, fearless adventurers band together in search of fame and fortune within the underground labyrinth known as the Dungeon. But Bell Cranel, novice adventurer, has bigger plans than riches and glory.