Mass Hysteria

"When humans are imagining something out of anxiety or fear, what they imagine remains behind, collects, haunts, and can even take on concrete form. That's how there can be a spider with gorilla legs lurking in the darkness underground, how people can die painting pictures of the Mothman on land, and why Gremlins appear in the air."

- Penelope de la Rosa

Mass Hysteria (集団ヒステリー) is an unusual phenomenon affecting several civilians throughout the world in both the original and 37th universes, featured in the light novel .

Surreal creatures appear in front of people when they are afraid, leading to an endless cycle of people spreading messages about seeing the creature and striking others with fear.

Summary
"When people are uneasy, they see things that aren't there, and not just illusions... They make it actually happen. Their fears manifest, and their plane gets damaged just as they imagined."

- Lisa Lisa

The concept is loosely based on a where collective illusions of threats, whether real or imaginary, is transmitted through a population in society as a result of rumors and fear. The fears, paranoia, and imaginations of people manifest into surreal beings. They are based on, also known as Unidentified Mysterious Animals (UMAs) in Japan. Rumors of seeing these creatures spread among the locals, developing their collective hysteria. Extreme cases can eventually lead to people attempting to kill themselves while in a hypnotic state. The creatures can disappear when people either get over their fear, or their fear disappears.