Split the Border

In July 2019, the world's first "border-splitting incident" occurred. A certain mountainous county lost contact with the outside world overnight. After 72 hours, the blockade is automatically lifted. All the 170,000 people in the city survived—— But no one remembers what happened during those three days. There is a "blank" in their memory. Since then, similar incidents have occurred one after another around the world. The frequency ranges from once a year → once a quarter → several times a month. In each event, the affected area will be "peeled off" from the real world. Internal physical laws, time flow, cause and effect—— will be replaced by an unfamiliar set of rules. At the outer edge of the peeling area, there will be a "border line" invisible to the naked eye. Ordinary people who cross the border won't die - but they will lose their memories of what's inside. A very small number of people who cross the border retain memories - they are called "observers".