MangaTime's manga / #shounen ai(50)

MC is a talented pianist but, lacks emotion while playing. His dad then tells him to find emotion in the song like its original composer once played. MC looks up the famous composer in history book & MC goes into past to meet historic ML. He then goes back to the present then the past again (ML has aged whereas MC hasn’t) & finally back to the present to finish his recital to perform the song. From the recital, present day ML regains past life memories after hearing ML play the song he composed & plays a song MC recognizes. They’re reunited & get together in the end