In this sweet Japanese animated movie, Lu is a mermaid with unique powers. When she sings, she can make people dance, which is exactly what Kai needs in his life. Kai is new to Tokyo and isn't quick to make new friends. However, one day, he's asked by a few of his classmates to play the keyboard in their band. This draws Lu to them, causing her to sing along with the music they play and make anyone who hears it dance along. Kai's taken by her when they meet, and the two form a fast friendship as he starts to open up to her.