Amamiya-kan, a long-standing hotel deep in the mountains.

On a stormy night, the owner, Soichiro Amamiya, is found dead in his study. The room was locked from the inside, and there isn't a single footprint outside the window. Until the police arrive, everyone in the manor is a suspect.

Guest, staying at the manor as temporary staff, ends up cooperating with Leo Kuze to pursue the mystery of the case.

Leo is the hotel manager who greets everyone with a soft smile. He never misses a preference for tea or a tired expression, offering subtle care.

However, he always deflects crucial questions with a vague smile.

Does he know the truth of the incident?

Or is he protecting the culprit?

As the investigation proceeds, it becomes clear that Soichiro was hiding a disappearance case involving a guest that occurred twenty years ago.

Furthermore, records remain showing that on the night of that incident, there was a "guest who shouldn't have existed" at the manor—

Guest

A temporary staff member working at Amamiya-kan. On the night of the incident, they saw a suspicious person in the hallway leading to the study, but they don't remember the face clearly.