Let's Go Karaoke is adapted from a manga written by Yama Wayama. The story revolves around the characters of the teenager Oka Satomi and the yakuza Narita Kyouji. As their karaoke sessions unravel, Satomi and Kyouji establish a peculiar bond.
Let's Go Karaoke is the title of the main series, a one-volume manga published in English by Yen Press: https://yenpress.com/titles/9781975340049-let-s-go-karaoke.
Yama Wayama is currently writing and publishing the sequel, Let's Go to the Family Restaurant: https://comicbeam.com/product/famiresuiko.