Chapter 4

 is the fourth chapter of the OnePunch-Man manga series.

Summary
Saitama is asleep in his apartment, but wakes up suddenly when his wall explodes and a hand reaches in and grabs his head. Saitama punches the arm of whoever grabbed him and the hand lets go, but he is then punched in the face, sending him crashing through a wall and down to the street below. When Saitama lands, his forehead is bleeding, but he has hardly any time before a creature pops out of the ground behind him and swings at him, sending him flying even though he attempted to defend, and when he gets up, he sees more of the creatures coming out of the ground. These creatures reveal themselves to be the Underground People, and intend to take over the world, they surround Saitama and begin to attack him. Saitama takes one out, but is quickly attacked by another. Saitama then rushes into the group of enemies, fighting madly until all of the Underground People are dead at his feet. As Saitama is standing there on the corpses, he hears a voice behind him and turns to see the Underground King bursting through the ground and is about to fight him when he hears his alarm clock go off and wakes from his dream. Sitting there stunned and dissapointed he hears the Underground King yelling outside, so he goes and kicks him in the face, killing him in one hit, and is about to fight the Underground People, but they had retreated back underground, leaving a white flag with the words "We're Sorry" on it. Saitama is severely disappointed.

Characters in order of appearance

 * 1) Saitama
 * 2) The Underground People
 * 3) The Underground King