Naoto Matsumoto is a young man who suffers from a peculiar memory loss: he does not remember his life before he was fourteen. Apparently both his parents died, and he was taken in by another family. On one rainy day, during a trip through the countryside, Naoto's car reaches a dead end on the road, and he and his stepsister are invited by a maid to spend the night in a large secluded mansion. Naoto witnesses increasingly strange and violent events and begins to recollect his lost memories.