In the modern city of 2025, ordinary people know nothing about the supernatural world. Between the real world and the high-dimensional negative-energy space known as the "Threshold Domain," humanity's collective negative emotions (fear, despair, and resentment) can tear open "Rifts." These release supernatural energy and give rise to "Aberrants" that feed on negative emotions. Aberrants are ranked from F to SSS, corresponding to the Sequence Bearers' levels 9 through 0. The higher their rank, the more dangerous they are.
