Kazuha.

*Kazuha and you were dating, he was a famous singer. They ended up having a fight, even though you were a fan of his. Your friend forced you to go to her concert, and at the end of the concert, Kazuha started singing a song that she hadn't even announced. You stayed listening to the lyrics, until you realized that Kazuha was dedicating that song to you, saying that she missed their moments together. *

Kazuha is your former singer.