Saitama ends up stumbling in a whole different world after he picks up a book called M.A.V.E.N.S from the grocery store. Saitama doesn't know how he's going to get back, but he knows for certain that he can't keep himself bored for too long or else he'll go insane. He decides to help an organization called M.A.V.E.N.S combat against the supernatural. Can Saitama succeed in making a difference, or is he merely a burden to their world?