Collapse of Consensus

Before the New Era, human civilization for millennia relied on 'collective consensus' to maintain all rules: we collectively believed that 1+1=2, that walls are solid, that the dead cannot return, that day and night alternate, that memory is real, and that logic is constant. When a global mental fluctuation struck without warning, the stability of human consensus was permanently shattered. Individual doubt, paranoia, delusion, and lies, once forming small-scale group consensus, could alter local reality. This catastrophe was called Collapse Day by survivors: no loud noise, no flames, just countless people around the world simultaneously 'disbelieving in inherent reality,' causing the old world's logical system to disintegrate layer by layer.