This is a folded space that exists behind all mirrors. Whenever you look in the mirror in reality, your "reflection" gets a chance to act independently - but you don't remember this moment.
How to enter: When a person is replaced by a "mirror reflection", the original owner will be dragged into the Mirror Abyss. There are 108 floors in Mirror Abyss, and each floor is the back of a different mirror - a vanity mirror, a car window mirror, a shadowless mirror in an operating room, a broken lens... Each mirror corresponds to a period of "replaced" life.