Genos vs. G4

Genos vs. G4 is a battle between S-Class hero Genos and The Organization's Demon-level monster G4.

Prelude
Saitama and Genos are out grocery shopping, when they see the S-Class hero King. Genos tells Saitama that the man in front of them is King, although Saitama does not recognize the hero. Moments later, a monster appears, terrorizing the civilians of M-City. At first, Genos believes that he and Saitama should help the civilians, but quickly changes his mind, deciding that the situation is a good opportunity to see King's fighting ability. The monster terrorizing the city is revealed to be G4, a Machine God created by The Organization. G4 quickly approaches King, and says that he will obliterate the hero. G4 demands that King fight at full strength, to which King complies. However, King asks to use the bathroom before fighting, claiming that when nature calls, he can only fight at half strength. G4 tells King that he will wait ten minutes, and for every minute King is late, he will kill one person. It is revealed that King is not strong, and instead ran away to hide. Although he feels guilty for his actions, he is too scared to come back. Due to King's absence, Genos ends up engaging in battle against G4.

Battle
Genos breaks G4's sword, then initiates a Rocket Punch, sending the robot flying. G4 manages to get back up with the use of his Back Thrusters, and proceeds to attack Genos with a downwards kick. Genos manages to block the attack, but has taken minor damage. Saitama asks Genos if he needs any help, but Genos refuses, stating defeating G4 would be a perfect opportunity to reach his goal in reaching top 10 in S-Class. Genos then breaks through the foot of G4, and continues his battle, while Saitama leaves the scene. Genos and G4 clash and as Genos leaps in the air, he punches G4 and uses Incinerate to melt the internal structures of the robot, claiming that its big body was its downfall. Moments later, the large body of G4 completely melts to reveal the true form of the Machine God. Although much smaller now, G4 continues his battle against Genos by unleashing a barrage of Laser Beams, one of which cuts off Genos's right arm. Genos tries to dodge the lasers and hides inside a building. To counter the lasers, Genos throws a fire extinguisher which exploded and malfunctioned the robot and then unseals the end of a nearby pipe, which produces a large amount of steam. He then restrains G4 with a cable from his severed right arm. G4 attempts to fire its lasers but finds it impossible to focus his lasers with the cloud of fire extinguishing solution draped around him. Genos tells G4 that he is stronger, as he is about to defeat him and both engages in hand-to-hand combat. It is later revealed that Genos has won the fight, but has sustained severe damage to his face and body.

Aftermath
Genos goes to Dr. Kuseno's laboratory, and gives him the remains of G4. He tells Dr. Kuseno to use the remains on himself, in order to become stronger.