One-Punch Man Episode 2: The Lone Cyborg

Saitama waters his cactus in his apartment while the TV news warns of a massive mosquito swarm heading toward Z-City, urging people to stay indoors. A single mosquito buzzes around him, evading his repeated swats despite his efforts.

In the abandoned streets of Z-City, a looter scavenging amid the evacuation has his blood drained by the swarm, revealing **Mosquito Girl** as their controller, a monstrous woman who commands them to feed. **Genos**, a powerful cyborg, arrives to confront her; immune to the mosquitoes as a machine without blood, he incinerates clusters of them with his arm cannons but loses an arm in the exchange after she severs her own legs to dodge his attacks.

Mosquito Girl absorbs the blood collected by her swarm from drained animals in the area, bulking up into a massive, empowered form. Genos unleashes a devastating energy blast that incinerates the entire swarm and much of the city district, stripping Saitama—chasing his apartment mosquito outside with bug spray—of his clothes, but fails to harm her. As she prepares to finish the damaged Genos, Saitama arrives, slaps her into the sky with one hand, defeating her instantly.

Genos, scanning the scene, realizes Saitama defeated her effortlessly and begs him to become his disciple. Back at Saitama's apartment, Genos recounts his full backstory: four years ago, a rogue cyborg destroyed his town and family, leading a scientist to rebuild him as this cyborg body in exchange for hunting that enemy down; Saitama grows impatient with the lengthy tale and agrees to train him just to move on.

Their talk is interrupted when a monstrous mantis creature from the "House of Evolution" bursts through the wall, proclaiming a message before Saitama kills it with one punch. Soon after, **Armored Gorilla**, a hulking cyborg minion of the House, smashes into the building, trapping Saitama underground in the rubble while challenging Genos. Genos battles Armored Gorilla fiercely; Saitama quickly digs out and defeats several more House minions off-screen, then shatters Armored Gorilla's armor with a single punch.

Interrogating the defeated Armored Gorilla, Saitama learns his gang was sent to eliminate threats but realizes they were all killed; the gorilla surrenders, admitting his robotic voice was just for intimidation. In a secret facility, a scientist named **Dr. Genus** monitors Mosquito Girl's defeat by Saitama on screens and orders his capture for experiments. After the credits, Dr. Genus enters a room of his worried clone subordinates, who question the failed Z-City team's fate.