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 analyses 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.

Characters in order of appearance

 * 1) Saitama
 * 2) Genos
 * 3) Mosquito Girl
 * 4) Dr. Genus
 * 5) Kamakyuri
 * 6) Slugerous
 * 7) Frog Man
 * 8) Beast King
 * 9) Ground Dragon
 * 10) Armored Gorilla

Manga & Anime Differences

 * In the anime, Saitama is not watching tv when the mosquito threat against Z City is announced, so he doesn't react to the news.
 * In the manga Genos is not shown until he confronts Mosquito Girl. He is also covered in mosquitoes at that moment, but was not in the anime.
 * In the manga, Genos explains his theory on the mosquitoes behavior before attacking Mosquito Girl. In the anime, he attacks first.
 * Genos and Mosquito Girl's fight was altered in the anime.
 * In the anime, Mosquito Girl does not specify that the range she is calling mosquitoes from is 50km.
 * In the manga, Saitama does not have bug spray when chasing the mosquito.
 * Genos' range of damage when destroying the mosquito swarm is much larger than in the manga.
 * Mosquito Girl does not destroy a building to prove her power after absorbing blood in the manga.
 * Mosquito Girl tears up Genos on the ground in the manga, while it was in the air in the anime.
 * In the anime, Mosquito Girl's blood sac splatters against the building. In the manga, she broke straight through it.
 * In the anime, Genos does not introduce himself before asking to be Saitama's disciple.
 * In the anime, Genus is not informed by his clone that Mosquito Girl was beaten after absorbing a large quantity of blood.
 * Saitama does not think to himself that Genos is weird when he detects something approaching, in the anime.
 * In the manga, Saitama punched Kamakyuri before he could finish his sentence. In the anime, he paused before he finished it and said an "Eh?" and was then punched.
 * In the manga, Armored Gorilla attacks with his left side and Genos blocks with his left. It is the reverse in the anime.
 * In the manga, Genos turns around after blasting Armored Gorilla to go help Saitama. In the anime, Armored Gorilla attacks almost immediately after the blast while Genos is still facing him.
 * Beast King does not wait for Saitama to shake the dirt out of his pants in the manga.
 * Saitama appears directly in front of Ground Dragon underground in the anime. In the manga, he appears from the side.

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.