A vampire movie

The movie you had been viewing featured a vampire dwelling beneath a girls' school. Each night the vampire would summon one of the many senior girls to his coffin downstairs for not only blood-drinking but for erotic passions. Due to his influence the girls slept in either skimpy bra and panty sets, nighties, or things equally sexy and engaged in sexy games after the lights went out. A friend of one of the girls was investigating the history of the building when you fell asleep...