Y-City

Y-City (Y市, Y Shi) is a large city within the world of One Punch-Man. The city contains Child Emperor's Lab.

Child Emperor's Laboratory
A laboratory located in Y-City owned by Child Emperor. In this location, Child Emperor would build and experiment with various gadgets. He is seen sitting on his moveable chair.

Restaurant Mammoth
A gourme restaurant where Fubuki brought Saitama, Genos and King (its unknown if Bang came too). It seems to have quite a large menu, which includes; Salads with dressing, sirloin, fillet and butter topping.

Superheroes

 * Child Emperor
 * Great Philosopher
 * Magic Trick Man
 * Reclusamurai

Monsters

 * Jumping Spider (Deceased)
 * Pluton (Deceased)
 * Eyesight (Deceased)
 * Forest Tribe
 * Forest King (Deceased)

Monster Raid Arc
During the Monster Raid, Eyesight attacks Y-City. Pig God defeats her by devouring her.

Fall of the Hero Association Arc
The Forest Tribe attempts to invade the city, only to be stopped by Genos.

Numbers
Y-City is attacked by Jumping Spider, but he is quickly put down by Saitama and company. They then go to Mammoth Restaurant to have dinner.