Countless worlds in the universe exist in parallel.
The survival or destruction of one world has no effect on the other. The sun still rises in the east and sets in the west.
But sometimes... Perhaps due to architectural errors, there is a connecting passage between the two worlds.
There are no rules or laws for the emergence of this channel.
A sea that you will never come out of again, a town that disappears out of thin air...
Silver diamond-encrusted diary.
The passage that shouldn't appear gives people from two different worlds an opportunity to talk.
It's just... Whether this opportunity brings new hope or more nightmares... It's unknown.