Angel's 3Piece!

Overview

Kyo Nukui is one of those shut-ins you hear about sometimes. He never goes to school, or even leaves the house. Instead, he composes music all day, uploading it to the internet for a few views. One day out of the clear blue, he gets an email from what sounds like an older, distinguished gentleman who wants to discuss music face-to-face. Having no one to speak to about his passion, Kyo accepts the invitiation... only to find himself facing down three elementary school girls! They're fans of his music, and they want his help to hold a concert at their orphanage. The girls prove to be good musicians in their own right and have excellent equipment, but is Kyo a good enough producer? (Source: Discotek Media)

Source: AniList