This novel reminds me of "Superstar of Tomorrow" which has the same setting: mc originally came from the apocalypse but died before it passed, the he reincarnated into the modern future days where he reignited his passion for music and started performing outstandingly. There's no shitstem bs, mc is also very mature and cunning, op af due to being a veteran and also extremely talented in music. Although that novel is very opposite to this simply because it has no romance whatsoever.
It is one of my favorite novels with musical theme, and this one might just be added to the list.
