In this chapter, we learn more about Tanaka's weird notebook, which contains information about demons. Tanaka asks if there are any demons that can possess on touching his notebook, and dairou answers that there are, but that they can't control the human body because it doesn't have any spiritual qi. A spiritual parasite is like a demon, but it can only control the host by force. In other words, the host can have dual pupils or triple pupils, or even piercing eyes, which is what we're talking about in this chapter.