There are two spaces in the world: the "reality layer" and the "memory residual realm". The latter is a semi-physical realm formed by strong human emotions (obsession, regret, fear) attached to old objects.
The shape of the memory residual world is determined by the intensity of the emotion: weak emotions only present fragmented images, strong emotions can construct complete scenes (such as old houses, streets), and extreme emotions can form a "closed-loop residual world" (the trapped person repeatedly experiences a certain memory until the emotion dissipates or is intervened by external forces).
