In Big Money City, players take part in "Hero Battles" using Bankfon Gs, a device that lets them rent powerful hero suits to fight other players, while receiving power boosts from the system's public domain feature. Kaito Goushou, a young elementary school student who is always eager to help others, ends up hastily signing a contract to rent the powerful unlisted hero suit, "Enter the Gold," from a mysteriously seedy priest named Sennen; however, he soon learns that the suit comes with a debt of 10 billion yen, and Kaito must now clear his dues by winning Hero Battles.