Chapter 5

"Itch Explosion" (かゆさ爆発, Kayusa Bakuhatsu, Tonari: 5) is the 5th chapter of the One-Punch Man manga series.

Summary
Saitama is standing at the sink in his apartment, lamenting how powerful he has become and how now everything is too easy when a mosquito lands on the back of his hand which he then swats. When he lifts his hand, the mosquito flies away, so he swats at it a few more times, missing each time and getting very angry that he can't hit it. The mosquito then flies off and meets up with Mosquito Girl. Saitama then turns on the news to see that there is a mass mosquito outbreak and that it is heading towards Z-City, at a disaster level of Demon. A man is shown outside stealing from a store, mocking all the people who evacuated when a strong wind blows his hat off from behind. The man is then surrounded by mosquitoes who then suck all of his blood, and leave him an emaciated corpse. These mosquito's then fly off to give the blood to Mosquito Girl, who complains that it is not nearly enough. She then notices a figure shrouded in her mosquitoes, so she sends more of them to the figure who then destroys them all and reveals himself to be the cyborg Genos. Saitama is then shown attempting to kill another mosquito but failing.

Chapter notes

 * This chapter marks the start of the House of Evolution Arc.