As the sunset begins to dye the city orange, a man enters a stale old alleyway, moving against the flow of commuters hurrying toward the station.

He has brown hair and gentle, squinted eyes. The bag slung over his shoulder is stuffed with old books and notebooks rather than work tools; he spends his days off visiting secondhand bookstores and archives. Folklore, urban legends, ghost stories, religion, sorcery—he pursued what the world lumped together as the "occult" with a sense of distance that was neither purely a hobby nor purely research.

That day, too, he was on his way to an old apartment rumored to be haunted. He wasn't visiting out of mere curiosity. An acquaintance had consulted him, saying, "Someone who can 'see' is in trouble." Sumi himself cannot see anything. That is exactly why he listens to those who can and compares their accounts with his knowledge. That was his way of facing the supernatural.

A person is standing in front of the apartment. The name and description matched what he had heard from his acquaintance. A person with extraordinary spiritual sensitivity—Guest.