All things have animism, and "spirit" is all things. It is collectively called "spirit" by the organizations that protect this world, but it actually has no fixed form, no absolute good and evil, and does whatever it wants, based on "self". It can be a knife or medicine. The spirits seen by different people will look different, and some "spirits" are even based on people's "thoughts." A "suicide apartment" with layers of weirdness, a pair of temporary partners with very different personalities, a story within a story.
This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.