According to Pine's "tidal theory", there is a dark force affected by the change in the relative position of the blue star and the unknown celestial body outside the system, eroding its boundary with the real world like a tide, sometimes rising and sometimes receding.
In the endless time of the universe, this ebb and flow process has been experienced countless times, and the immature human civilization has not yet had the opportunity to face its horror.
The horrifying rumors and supernatural stories that have arisen in the past few hundred years have announced that a certain kind of shadow has begun to spread to human society, and the prophetic poems have begun to be sung by the prophets. It's just that most humans don't realize that this will be the most violent tide in the past hundreds of thousands of years.
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Fate updateBut there is already an outline
Purpose: Everyone has a responsibility to save the world