Unusual

A demon has no gender. 

Speaking from a certain point of view, it didn't even possess a thought of its own.

All it had was a persistent grudge of the dead towards the living.

Of course, a demon wasn't categorized as a dead spirit. It was a lot smarter and a lot harder to deal with, not just because it was good at hiding, but also because of it's powers and traits.

The undying traits of a demon could cause a headache in everyone easily.

A Superior Demon was a special one, even among the ranks of demons.

It was in [Hetero-form] from the start!

Its undying trait, which had gone through multiple enhancements and was far stronger than a common demon, its extremely high intellect and related Mystical Knowledge, all its enhanced traits made it different from a common demon.