Kaito Gōshō, who helps out others with his friends Mitsuo Zaizen and Fukuta Kanemaru, rushes to the aid of their companion, Nagare Amano, who is being bullied. Kaito manages to get back Nagare's wallet by beating one of the bullies, Raigo Raigou, in a Hero Battle, a digital battle game using rented battle suits powered by support from spectators. Later that day, Raigo brings his older brother, Shuuto, to challenge Kaito to another match for revenge, deciding to make Kaito his henchman should he win. However, during the middle of the battle, the rental period for Kaito's 'Bad Boy General' suit expires, leaving him naked and defenceless. Just then, a strange man named Sennen appears before Kaito, offering him a contract for a powerful hero suit called Enter the Gold. Kaito hastily accepts the contract and uses Enter the Gold to defeat Shuuto and win the match. Following the match, however, Kaito learns that the fee for renting this suit is ten billion yen. Meanwhile, Nagare is approached by a mysterious figure, who offers him the same kind of power Kaito has.
