Dear Pianissimo (2006)

Shu works at a pizza restaurant. When he is on his way to deliver, he sees Nagi, who wants to be a voice actress, practicing at a riverside. When he is on his way back to the restaurant, he sees Nagi again but they get involved in a truck accident and lose their lives... They come to a school located between this world and that world called "Conservatory". They wake up and find out the fact that there is a way to go back to this world. It is necessary to win a music contest done one-on-one. This means a winner can go back and a loser can't. Ironically, Shu is going to have a one-on-one match against Nagi, who is actually tone-deaf... Shu suggests that they practice together until the contest day...