Chapter 3

A Dangerous Being (災害存在, Saigai Sonzai) is the third chapter of the One-Punch Man manga series.

Summary
The chapter opens on Fukegao, who has just finished his new, ultimate steroid, Biceps Brachii King. Fukegao gives his new steroid to his little brother, Marugori, claiming that it will make him the strongest man alive. Beefcake drinks the drug and his body immediately starts to transform, growing till he crashes through the ceiling and becomes taller than the surrounding hills. Marugori picks his brother out of the rubble of the building and sets him on his shoulder, who then proclaims them The Brain and Brawn Brothers, the strongest, most intelligent group in the world. The two of them head to the nearest civilization, D-City, the entirety of which he destroys in one swing of his arm, Fukegao then says to go on and destroy the next city.

The country is in uproar and multiple news stations report the disaster. As they head to the next town, B-City, Fukegao notices that there is someone sitting on Marugori's other shoulder, that someone being Saitama. Marugori mistakes which shoulder Saitama is on and accidentally swats the shoulder his brother is on, killing him. Beefcake then freaks out, lamenting that all he'd wanted was to have more power, and blames his brothers death on Saitama, grabbing him off of his shoulder and throwing him to the ground. Saitama begins to get up and brush himself off when Beefcake jumps on top of him and starts pounding Saitama back to the ground. Thinking he'd beaten him, Marugori goes to walk away when Saitama jumps out of the hole and punches Marugori in the face, killing him, and says "Having an overwhelming power is boring as hell." Marugori then lands on B-City, destroying it.

Characters in order of appearance

 * 1) Saitama (cover)
 * 2) Fukegao
 * 3) Marugori