The Mosquito in *One Punch Man* appears during one of the early episodes and serves as a humorous yet deadly threat. It is part of a swarm controlled by Mosquito Girl, a mosquito-themed villain who commands hordes of blood-sucking insects. While the mosquitoes themselves may seem trivial, they are incredibly dangerous in large numbers, capable of draining the blood from their victims within moments.
The most memorable scene involving the Mosquito occurs when Saitama tries to swat a single mosquito in his apartment. Despite his immense power, he finds himself frustrated by the tiny insect, which dodges all his attempts to kill it. This creates a comedic contrast, as Saitama, who can defeat world-ending monsters with one punch, struggles against an ordinary mosquito, showcasing his human side.
The mosquito's antics add humor to an otherwise intense episode, where Mosquito Girl uses her swarm to grow stronger by draining the blood of humans and animals. Eventually, Genos confronts Mosquito Girl in a fierce battle, but it is Saitama who delivers the final blow, effortlessly defeating her with a single slap after her mosquito swarm proves ineffective against him.
The scene highlights *One Punch Man*'s blend of comedy and action, where even the smallest, most mundane challenges can become memorable moments. The mosquito, while insignificant compared to the series' larger threats, leaves a lasting impression due to its role in a humorous and iconic sequence early in the show.