It has been ten years since the demon king was defeated.
Ten years since all might fought his last battle and two years since the all for one hero returned .
During this time many things have happened,new heroes have emerged ,great villains have been put to justice and this is a golden age of heroes .as the world has day so shall it have night,in the background of this new world a great evil lurks in its night.
The story basically follows Takahashi rumi as she investigates a case about the mass disappearance of children across Japan.
This leads to the discovery of a new demon king who might also change the world.
The MC is a investigator ,these are people who are drafted as case investigators by the public safety commission due to having quirks suited to such.