CtrlK

Let's Go Karaoke!

Famiresu Iko.
ファミレス行こ。
패밀리 레스토랑 가자.
Andiamo al karaoke
Пойдём в семейный ресторан
去家庭餐厅吧。
去家庭餐廳吧。

Prequel

manga
Nothing worries Satomi Oka more than the upcoming final choir competition of his middle school career -- right up until he is accosted by a stranger from the shadows who demands, “Let’s go karaoke!” As a yakuza, Kyouji Narita doesn’t scare easily, but a terrifying prospect has driven him to seek Satomi’s help. The boss is holding a karaoke contest, with the loser forced to get a tattoo to be selected and torturously applied by the boss himself! Oka has been to many vocal rehearsals over the years, but never one-on-one karaoke sessions with a gangster!! 

(Source: Yen Press) 

*Notes:
\- Originally released at COMITIA 129, was then licensed by Kadokawa for commercial release.
\- Includes one extra chapter.*