Fuyumi Yanagi
The human high-school-aged girl who becomes lost in the Demon World through unknown methods and becomes a ghost after being eaten by a carnivorous plant. The triangle headband that she always “wears” is a symbol of this.
Fuyumi is (or was) a human girl from Japan, and because of this Staz became even more interested in her; he often asks her about anime and manga from the human world. She wishes to be resurrected as a human, and to help Staz achieve that goal.
It is later revealed that she became the sister of Hydra Bell, and the “daughter” of Neyn after she learns what happened to her missing mother.