Based on a game by CLOCKUP
Cannone is a violin that entrances people. Ceillia is a violin that was created by the angels that seals Cannone.
Akio became a teacher for St. Cecillia Academy. He found Cannone sealed in the torture room under the chapel, he was fascinated by it`s power. The other violin picked a girl to use it`s powers to steal Cannone.
(Source: Animenfo)