J-City

J-City (J市 J Shi) is a large, seaside city within the world of One-Punch Man.

Heroes

 * Stinger

Monsters

 * Seafolk (Extinct)
 * Sea King (Deceased)

Sea Monster Arc
J-City is invaded by Seafolk. A-Class hero Stinger is able to fend most of them off until the Sea King arrives. The Sea King rampages through the city, causing chaos and defeating heroes like Lightning Max, Puri-Puri-Prisoner, License-less Rider, and Genos, before being stopped by Saitama.