Kentaro Yamamoto (voiced by Daisuke Ono), a steady and reliable elder brother who is trusted by his younger brothers, Ryo Tachibana (voiced by Satoshi Hino), who has a hot temper and always acts before thinking, and Kazuya Sugihara (voiced by Kazuyuki Okitsu), who is full of longing for the life of the underworld and longs to do something big, are the iron triangle in the underworld. However, because they did something wrong in an accident, they are about to be punished by the boss Inugane (voiced by Keiji Fujiwara). Inugane gave them two choices, one is to die to apologize, and the other is to be sent to Thailand for sex reassignment surgery and then debut as an idol group. In the end, the three chose the latter, and in this way, the idol group Backstreet Girls with Airi (voiced by Yuuka Nuri), Mari (voiced by Kaori Maeda) and Chika (voiced by Hikaru Akao) as the core members was born.