The system is called "Corridor", and the entrance is a paper figure (with the name of the lost person written on it) that appears on the pillow. The penalty for failure is that the consciousness is assimilated into a copy of the NPC. The points are called "paper money", and the skills are divided into three categories: active/passive/exclusive. The heroine's exclusive skill "memory retrospection" comes at the cost of randomly losing her own memory. The main suspense is gradually revealed in 12 levels, with one clue buried in each copy.
