A-City

A-City (A市 A Shi) is a large city within the world of One-Punch Man. It is the location of the Hero Association headquarters. A-city was completely destroyed by the Dark Matter Thieves, so it is now only inhabited by Hero Association staff and heroes. Metal Knight re-built A-city into an expansive headquarters for the Hero Association with highways leading to all other cities.

Inhabitants

 * Sitch

Monsters

 * Skyfolk
 * Sky King (Deceased)

Saitama Introduction Arc
The monster, Vaccine Man, attacks the city. Lightning Max and Smile Man are sent to defeat him but are defeated. Later Saitama shows up and defeats Vaccine Man with a single punch.

Rumored Monster Arc
The council of the Hero Association calls up the heroes to check in on their cities.

Alien Conquerors Arc
Boros and his Dark Matter Thieves attack the city in order to find the worthy opponent of a prophesy that Boros found. They were defeated by 6 S-Class heroes, Iaian and Saitama.

Psychic Sisters Arc
A-City is remade into a fortress by Metal Knight and all the A-Class and S-Class move there, including Saitama.