Underneath the superficial prosperity of modern cities, there are hidden "remembering spirits" that coexist with human beings - spiritual life forms condensed from memory fragments and strong emotions. The memory spirit is intangible and usually harmless, but the memory spirit carrying huge trauma or obsession can corrode the host's spirit, distort reality, and cause "memory disaster". The state secret agency "Memory Bureau" (referred to as "Memory Bureau") is responsible for handling these incidents.
