Sound Novel Evolution 2: Kamaitachi no Yoru Tokubetsu-hen

Toru and his girlfriend Mari are staying at a ski lodge when a snowstorm cuts the building off from the outside world. That evening, a note appears in one of the guest rooms: "Tonight, at midnight, someone will die." Shortly after, a guest is killed. Toru and Mari find themselves at the center of a murder mystery locked in by the storm, with a building full of people and no way to call for help from outside.