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.
Jinmen, the depraved turtle-like demon eats humans alive to devour their souls, leaving an imprint of them on his shell while they are trapped in agony. Jinmen targets vulnerable humans on purpose, with children being a favorite meal, including a 10 year old named Sachiko who had befriended Akira. Those he devours are left alive and conscious, but trapped until Akira kills him.
Candy from the AMON side story was a Serial Killer before achieving great power. In the post apocalyptic world, Candy ekes out a power base by convincing humans there is no such thing as Devilmen, resulting in purges of countless peaceful humans believed to be demons. Candy takes delight in the deaths of the innocent and simply enjoys wielding power over others.
Due to a notoriously mistranslated subtitled version of the 1972 anime, DEBIRU-Man has become a popular nickname for the title character.
Fridge Horror: In Devilman Grimoire, actually. Remember how, in the original Devilman, Miki and Tare were horribly murdered by a psychotic lynch mob consisting of their own neighbors, because they thought she was a witch? When one considers that the cast is pretty much the same in Grimoire (with a few additions), it stands to reason that the Makimuras' neighbors most likely are also the same people. Which then leads to the realization that the whole neighborhood is a ticking time bomb, ready to go off under the right conditions. It doesn't help that Miki goes around announcing to anyone who's willing to listen that she is a witch.
Then again, as of the latest chapters in Grimoire, Miki herself is now a Devilman, so killing her just became that much more difficult.
Narm: Satan's immortal line: "For, you see, I am a hermaphrodite!"
The Live Action Movie is filled with this.
Ryo's plan for turning Akira into Devilman involves gathering a bunch of hippies together in his basement. It Makes Sense in Context, yes, but it's hard to take the line "These people here are rouge hippies I've gathered together" seriously.