From Stage Storm:
Marie is the illegitimate daughter of an actor. After her mother's death, Marie transfers to a new school called "The Saint Rose Cruciform". The rules there are really strict; students can't leave, and they have no contact with the outside world. Soon she discovers they are worshipping a demon, and while she feigns to do so to keep living, her only friend Deborah is discovered and killed. She meets Carlos, a boy who wants to be a director, who gives her a camera so she can film what happens inside the school. She will try to expose it outside at any cost, especially when her father tells her he's going to marry an actress who worships the demon too.