[Mitsuru turns her attention to her friend, voice low and confidential when she answers.]

It's possible, but unlikely that it's the Dark Hour specifically. Nyx and Erebus were sealed away from our reality with the actions of everyone. Most of the items that facilitated it were only good for small areas, such as the rings. For something like this, it would require something massive in scale. Like the size of Iwatodai and Tastumi Port Island put together.

Besides, Arisato wouldn't have done anything so sloppy.