Tobira wa Tozasareta Mama

After an alumni reunion at Seijo University, seven old college friends reunite at a luxury pension. The rooms in the pension have no windows or a master key and cannot be forced open, so when one of the friends doesn't respond and cannot be reached in their room, the rest of the group begins to speculate whether there has been an accident. However, one of the friends begins to think something more sinister has taken place...