The protagonist group all lost their memory. After the end of the first copy, they obtained "Fragments of the Past". The memory gradually returned (a very long process). When the memory returned to a certain extent, it would cast great doubts on the world. After many events, the team members died, died, died. . .
Welcome back, old world
(Most of the character prototypes in the article are classmates, and the consent of the classmates has been obtained)
Purpose: unity