The start of a song

A new city a new start. After living in Tokyo for a few years, Hina, your average basic student, is starting her second year at Shinigawa high, and the school's recently hired music teacher Mr. Kazuki. As the year continues, 3 students are murdered. After an event Hina calls, "the song", happens she is sent back to the past to solve exactly what happened and prevent the students deaths. Will she be able to save them or will she end up dead instead?

(At the moment this will be a non gory story, if it does however I will mention it and change the story to mature. :))