Netherworld Archives

In an inconspicuous alley, there is an inconspicuous two-story building hidden. Of course, most people cannot see it, because this place disappears and appears, or it only appears at a specific time or place. It may be here this time, but it will appear in that place next time. Overall it's a very mysterious place. But I heard someone say that this place is called the Netherworld Archives. . . . . . . .