Okada Satoshi, a third-year middle school student and the head of the choir club, is suddenly approached by a yakuza named Narita Kyoji at the choir competition venue, who says, "Let's go sing karaoke!" I'm called out to. At the Matsuribayashi gang, where Kyoji is, there's an annual karaoke contest, and the request was for singing lessons so he wouldn't be crowned the worst singer.

Satomi finds himself having nightmares, only for it to worsen when a group of Yakuza ask him for help.

With the big day coming up, Satomi must sort his feelings as his time with Kyouji draws closer to an end.