The Doppelganger, Three Middle-Age Women, and Space-Time Man are all part of a single phenomenon
Refers to experiencing strange events that are related to the Otherside. A Phenomenon accompanies encountering one or more creatures taken from ghost stories or internet lore, sometimes taking a human form to interact physically, making it harder to distinguish it from reality.
According to Kozakura during their encounter with the Three Middle-Age Women, if the reflection of an external entity in a person's perception is not true to reality, then there is something strange happening in the brain's cognitive process.
