The president of the chorus club, Satomi Oka, is approached by a yakuza named Kyoji Narita. Kyoji's yakuza group holds a customary karaoke competition, and whoever earns the title of worst singer must get a tattoo. Since he was asked to be Kyoji's singing teacher, Satomi has no choice but to go along with these practice sessions. Brought together by karaoke, where will Satomi and Kyoji end up?