Lin Cheng has been different from others since he was a child. Things other than people are translucent in his eyes. Through houses and clothes, everyone's life is nakedly displayed in front of him. So he was sent to a mental hospital since he was a child. After coming out of the mental hospital, he was completely cut off from his previous life, immersed in his own life, and had no feelings for the outside world.
The doorman was killed at night, and Lin Cheng, who had talked to him last night, became a suspect. The police discovered that all the residents in this building had left or moved out of the building for various reasons before the incident, except for Lin Cheng and the residents above him.
The abused children across from Lin Cheng, the family who has been having dinner downstairs, and the otaku who is obsessed with playing computer games. They turned out to be all translucent. In other words, they are not human.
Conception: