Morioka Middle School's choir may have placed second in a national competition, but 39-year-old yakuza Kyouji Narita has judged them the best. The boss of his criminal family loves karaoke and tattoos—and he blends his hobbies by forcing every family member into a karaoke showdown, the loser receiving a hand-pricked tattoo of the boss' choosing. However, the boss is a complete amateur, and Kyouji is desperate to avoid becoming his next canvas.

To learn how to outsing everyone else, Kyouji seeks help from 14-year-old Satomi Oka, the head of Morioka's choir. Satomi sees little reason in Kyouji's actions and the ridiculous competition; he has his own worries, being in the middle of puberty and dealing with a changing voice that seems to betray him more each day. But feeling somewhat sorry for Kyouji, Satomi cautiously begins coaching him, trying to make sense of his uncertain teenage years and his new, offbeat friendship with a gangster.

Karaoke Iko was originally released at the doujin event COMITIA 129. It was then officially published by Kadokawa on September 12, 2020. The series ranked fifth in the 2021 Kono Manga ga Sugoi! for the Female Readers division. It was also nominated for the 14th Manga Taisho Award and placed third in the final ranking in 2021.

The series was published in English as Let's Go Karaoke! by Yen Press on May 24, 2022.

The manga was adapted into a Japanese live-action movie that was released on January 12, 2024.