Episode 2

"The Lone Cyborg" is the second episode of the One-Punch Man anime series.

Summary
While Saitama waters his cactus, the TV announces that the recent massive mosquito swarm is headed towards Z-City, 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 by Saitama in a single slap. In amazement, Genos asks Saitama to become his disciple, to which he complies. Genos appears at Saitama's door days later much to his annoyance. He explains his situation in a long-winded monologue which frustrates Saitama.

Elsewhere, a man in a secret facility analyzes Mosquito Girl's defeat and decides to capture Saitama for his experiments. Back in Saitama's apartment, Saitama and Genos' conversation is interrupted by the House of Evolution's messenger, who is promptly destroyed. Saitama is then trapped underground while Genos faces off against Armored Gorilla, another cyborg, although Saitama soon escapes. He quickly defeats his two opponents and then questions the defeated cyborg, who panics when he realizes the rest of his team has been destroyed. In the end, Doctor Genus steps into a room full of worried subordinates discussing the fate of the team in Z-City, when they turn around it is shown that they are all clones of him.

Trivia

 * S-Rank heroes Pig God, Superalloy Darkshine, Metal Bat and Watchdog Man all make cameos in the episode.
 * Mosquito Girl gives the episode monologue at the end of the credits.