In a world where K-On! members are caught in a web of musical conspiracies, one mysterious music box holds the key to their destiny. As they delve deeper, they must confront their own fears and the power of music itself....

In a world where music is a forbidden force, Mario embarks on a perilous journey to uncover the truth behind an enchanted music box, only to find that the melodies hold secrets more dangerous than he ever imagined....