Bye Bye Regret

Saaya has always been in love with Yuuki since high school, but she has never dared to tell him this, and when she tried to do it, she found herself doing something that she will regret for several years. One day, when she visited her grandfather, he gives her a small box of music with certain powers … Will she be able to make amends for his mistake or will her love for Yuuki lead her to make more nonsense?