Diamond City is a location found in the WarioWare video game series. WarioWare: Twisted! confirmed that Diamond City is located on an island, though the exact location is unknown. It's a large city that's not only represented in the WarioWare series, but was also found as a stage in Mario Kart Arcade GP, which showcased more buildings such as a headquarters for Professor E. Gadd's company and plenty of shops. This is where Wario, among other characters in the games, live. It is slightly different in each game. Club Sugar is a popular meeting place for characters there.