Subterranean civilization

Date: 9/17/2019

I’m in this community of humans trying to survive in this network of subterranean caverns and tunnels, thousands of years after our current civilization has collapsed. There are these dragon-like humanoids living below the surface with us, and also huge, demonic-looking constructs like in Miyazaki’s Nausicaa that roam the surface world. They’re responsible for the destruction of the earth. Like in Nausicaa, they were created for war, but they simply destroyed (almost) everything. Venturing to the surface is extremely dangerous. A disease has spread that causes some people to become extremely violent when exposed to light. Some time ago, someone discovered that some sound frequencies could calm the affected people, and prevent them from becoming violent. So, whenever it happens, people have to start singing the chorus from The Phantom of the Opera. Ridiculous, but okay.