While One Punch Man waters his plants, the TV announces that the recent massive mosquito swarm is headed to City Z, where he lives. He attempts to kill a mosquito but fails each time. In the abandoned city, a looter taking advantage of the situation has his blood drained by the mosquitoes, which are being controlled by Mosquito Girl. She fights with Genos, who as a cyborg is not affected by the swarm, each taking a limb from the other. She then powers up by consuming the blood gathered by her swarm from the animals in the surrounding wilderness. This causes the battle between her and Genos to become one-sided, but she is killed in one hit by One Punch Man. Genos appears at One Punch Man’s door a week later asking to be his apprentice. He explains his situation in a long-winded monologue which frustrates One Punch Man. Elsewhere, a man in a secret facility (who’s name was Doctor Genus) analyzes Mosquito Girl’s defeat and decides to capture One Punch Man for his experiments. Back in One Punch Man’s apartment, One Punch Man and Genos’ conversation is interrupted by the House of Evolution’s messenger, who is promptly destroyed. After going outside, Saitama is yanked into the ground up to his neck by a mole monster. Genos faces off against another cyborg alone. Saitama escapes and quickly defeats his two opponents. He then questions the defeated cyborg, Armored Gorilla, who panics when he realizes the rest of his team has been destroyed. After the credits, Doctor Genus steps into a room full of worried subordinates discussing the fate of the team in City Z, when they turn around it is shown that they are all clones of him.