Belphegor is rather short, especially when compared to other Demon Lords, and she looks to be in her mid-twenties. She is the only Demon Lord to have a human skin colour in, being a warm tan, and shoulder length white hair that is parted at the far left. She has very unusual eyes, with yellow sclera, white irises, and red pupils. For horns, she has two large white antlers with yellow thorns protruding from them like the stem of a rose. She has wings of bone, connected by white skin. Her tail is fluffy and cat-like, with a flytrap-esque mouth at the end.
- Belphegor has an extremely high resistance to poisons, which includes alcohol, so the alcohol she drinks is so strong that it's lethal in relatively small doses to a normal person.
- Belphegor is the shortest of the Demon Lords, being a whole 13 centimeters shorter than the second shortest original Demon Lord, Beelzebub, and being slightly shorter than Charlotte as well.
- The mouth on Belphegor's tail seems to lead to her stomach, seeing as she often drinks with it to avoid tasting the potent alcohol she relies on to get drunk. On occasion she eats with it too, but it's usually people she eats with it.