High schooler Akira was raised as the heir of Kikunoyu, a sento bathhouse run by his grandfather and mother. He always had dreams of becoming a hero. But he quit baseball, which he'd been playing since he was young, and spent his days going to karaoke after school with his childhood friend Kacchan. One day, Kacchan receives an email from the idol talent agency sMiLea Production on a recommendation from the legendary idol Anela. Although Akira has no relation to it, it seems that he might be involved...

At the live performance, Akira is moved by the presence of Daiki, who looks like the main character of Akira's favorite hero anime, "Crossfire." Revved up, Akira and his group get inspired for their lessons, but the dance lessons particularly seem hopeless. Later, it's decided that the three of them will get to participate in a commercial shoot as LEGIT's backup dancers. Although there's not much time before filming begins, LEGIT gives them one-on-one dance lessons. Akira, who fretfully practices yet makes little progress, begins feeling impatient and makes a proposal to Banri and Chihiro.

As PROTOSTAR, Akira, Banri, and Chihiro successfully completed their live debut. But for some reason, Chihiro seems conflicted. In actuality, Chihiro is the eldest son of a famous Japanese dance master. Chihiro, unable to get into the swing of practice, is severly troubled that he cannot tell his father he is an idol nor can he tell his friends the situation. Worried about Chihiro who keeps skipping lessons, Akira and Banri visit Chihiro's house──?!