. I remember it was at the end of a manga book that i read.
So does anyone know the oneshot or the Manga book it was in?

It was a one shot about the main character(female) who met the vocalist that sang her favorite song when she filled in a part time for someone
They ended going out together during one of his auditions and they preformed with this street performer for fun. When the girl returned to the studio she wasn't allowed in but at they ended up together at the end.

Something along those lines
Anyone might recall the book title or story title?

Whew, I've wretched my brain for days now 'cause I couldn't remember the title of this one, but finally (and coincidently) I found out! 😀 😎 Err, well, at least I hope it's the right one 🤣
Isn't it the extra story in volume 1 of Asa Mo, Hiru mo, Yoru mo, the one called "I Will Wait For You Backstage"?

I sold my soul to The Devil, but now the bastard wants his money back!