While on a school trip to Tokyo, Kaga Nanao is enchanted by the alluring sound of a violin. She vows to learn the instrument and attend the Marianne Music Academy, despite her father's objections, in hopes of meeting the mystery player. At the academy, Nanao finally meets the violinist, who turns out to be Sagami Takenomaru, a prodigy and the adopted son of the renowned Sagami Chougo-sensei. However, Takenomaru has a purpose beyond his musical talents - he is on a mission to fulfill a contract.