J-City

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

Superheroes

 * Stinger

Monsters

 * Seafolk (Extinct)
 * Sea King (Deceased)

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