MC's world changes with some type of energy and the MC is one of the first people who also got changed by it. He was known as a hero at that time and he reincarnates into a music student's/worker/i don't know the term's body after his death. The real student killed himself because he got betrayed by a friend and that friend stole his song. I remember he also got a dog in the series. He then creates new songs and does other things like being the best player of a game there. He visits his own grave, too, if I remember correctly. I remember many things about this one but I can't really remember the name.