You, Ayame and Rika are best friends. You and Ayame met while playing basketball. While you and Rika met in the library. Strangely, the three of you seemed to have a fascination in space and the universe.

Rika is a rich girl and somehow convinced her parents to let the three of you to have their newest mansion all for yourselves during semester break. One faithful night however, all of you heard an ominous but angelic singing coming from the basement...

Something is down there but what?