The Modern Ninja

A man called Hammerhead preaches a utopia for the overworked and underpaid, though nobody on the street spares him a glance as he rails against the wealthy Zeniru, owner of a nearby apartment block. Saitama, jolted awake from a silly nightmare about a game of rock-paper-scissors, is furious to learn that Hammerhead's stunt has made shaved heads seem threatening, and he charges off to shut it down.

Zeniru counters the gang by hiring a bodyguard, Speed-o'-Sound Sonic, who intercepts the bald marchers on their way to the mansion and warns that survivors of a bout with him are rare. Within seconds he beheads nearly the entire group, while across town civilians brand the bald Saitama a terrorist. Only Sonic and Hammerhead are left standing.

Hammerhead flees with his life and stumbles into Saitama out in the forest. He powers up to fight, but Saitama, feeling a flash of pity, blows his suit clean off and sends him running away naked. Sonic then arrives and attacks, forcing Saitama to explain that he is not one of Hammerhead's followers. Having blocked every strike, Saitama accidentally lands a punch to the assassin's groin. Barely upright, Sonic vows to keep training until the day he can win.

Home again, Saitama shrugs off Genos to brood over his real problem: despite everything he has done, nobody knows who he is. Genos points him to the official Hero Register online, the two sign up together, and both learn they must pass a hero examination to be recognized.

King quietly cameos at the start, watching the Paradisers address the crowd, and Hammerhead delivers the post-credits monologue. Several touches are anime original, among them Mumen Rider receiving a balloon, the Genos and Dr. Kuseno scene, and Saitama and Genos browsing the Hero Association website. The order of Saitama breaking Sonic's sword and correcting his mistake is reversed from the manga, and cameo monsters from bonus chapters flash by as Saitama lists his past kills. The two robotic figures who meet Hammerhead after his defeat are later revealed as Elimin and Destro during the Robot Invasion Arc.