These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Blaster Knuckle
Humans Are the Real Monsters: Considering the era this manga takes place in, the demons are simply humans who transformed into the beasts within themselves and act out on their darkest impulses.