Situated within an endless twilight, the Tasogare Hotel welcomes anyone stuck between life and death. Unaware of their fate, guests must regain lost memories through mementos hidden in their designated hotel room. Most guests pass on or return to the world of living within days, while few others find themselves staying at the hotel for much longer than usual.

Neko Tsukahara, a young woman with an expressionless face, finds herself at this hotel. As she is guided along by the staff, Neko regains enough of her memories to become invested in the plights of the other guests. Solving the guests' affairs and the mystery behind the hotel turns out to be too interesting of a situation to pass up; Neko decides that simply being a guest is not enough to satisfy her curiosity.