There are 13 old doors engraved with symbols on the seaside black house. Each time they are opened, the entire house will be dragged into a "parallel timeline", but all lines will collapse and restart on the seventh day. The protagonist group discovered that after each restart, there would be one more corpse of "themselves" in the room, and the corpse number was gradually approaching 13. Who is Corpse No. 0? Why is the "clearance video" of the next cycle stored on my phone?
Concept: The biggest ghost of a person is his unborn self.