UNSUNG HERO

Unsung Hero summary:

(From MAL)
The stage is set when Ichirou Gomen, a newbie producer of the record company Gaia loses yet another production opportunity to inexperience. Wanting to pass on his childhood dreams of stardom to a fledgling singer, he toils learning the process day by day through failure.
However, his life is sent into a loop when he follows a beautiful performing voice, the voice of Jam Hiiragi, playing live to a group of homeless people at a streetside. Wrangling the prodigy talent and her bratty complications, together they face off and challenge the professional world of the music industry.