Kuroko's group goes to a hot spring deep in the mountains, where the entirety of the
land is owned by the wealthy Yamatsukami family. But right as the family is going to
decide the next heir, the third son is found murdered... To make matters worse, the
only road in and out of the area is suddenly destroyed! Cut off from the rest of the
world, the family begins to whisper about a mysterious "Ayako." With little to go on,
how will Kuroko solve this closed-room case?