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


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.

Characters in Order of Appearance[]

  1. Saitama
  2. Mosquito
  3. Mosquito Girl (Debut)
  4. Genos (Debut)

Chapter Notes[]

Online Cover


Volume 1 12345678Extra
Volume 2
Volume 3 1617181920ExtraSpecial
Volume 4
Volume 5 2526272829Extra
Volume 6
Volume 7 353637Extra 1Extra 2Extra 3
Volume 8
Volume 9 41424344454647Extra
Volume 10
Volume 11 565758596061Extra 1Extra 2
Volume 12
Volume 13 68697071ExtraSpecial
Volume 14
Volume 15 7677787980Extra 1Extra 2
Volume 16
Volume 17 858687Extra
Volume 18
Volume 19 91929394Extra
Volume 20
Volume 21 979899100101Extra
Volume 22
Volume 23 107108109110111112Extra
House of Evolution Arc
Manga Chapters 567891011
Manga Volumes
Webcomic Chapters 5 • 6 • 7 • 8 • 9 • 10 • 11
Fights Saitama vs. MosquitoGenos vs. Mosquito GirlSaitama vs. House of EvolutionGenos vs. Armored GorillaGenos vs. Carnage KabutoSaitama vs. Carnage Kabuto