Fuyumi Yanagi

Fuyumi Yanagi (柳冬実) is the human high-school-aged girl from Japan who becomes lost in the Demon World after traveling through the mysterious Black Curtain. She becomes a ghost after being eaten by a carnivorous plant, symbolized by the triangular headband she wears. After she becomes a ghost, Staz Charlie Blood vows to bring her back to life.

Physical Appearance
Fuyumi is a 16-18-year-old girl with shoulder-length black hair and large, dark, blue eyes.

Fuyumi initially wears a school uniform, though she frequently changes outfits throughout the manga. She was once a human but she is now a ghost. After her death, she always dons a triangle-shaped headband which is a common symbol to denote that a being is a ghost in Japanese culture.

Personality
Fuyumi is shown to be a kind, sensitive, and supportive girl; though, she can also be naïve and shy. She often finds herself surprised and sometimes annoyed by Staz Charlie Blood's lack of common sense, yet she eventually has unquestionable faith in him, although she isn't afraid to stand up for what she likes or what she believes in. She tends to act as a foil to Staz's more outrageous personality. She wishes to be resurrected as a human and strives to help Staz achieve that goal. It is also noted that she is excellent at using proverbs to describe the odd situations she finds herself in with Staz.

Plot
Fuyumi first stumbles into the demon world after walking through the Black Curtain in her room. After appearing in the demon world, she is brought to the Territory Boss, Staz Charlie Blood, the main protagonist of the series.

Since she is from Japan, and Staz is an otaku, Staz is even more interested in her, often asking about anime and manga from the human world. After Staz leaves to fight a challenger, she is eaten by a carnivorous plant and turns into a ghost as a result. When Staz learns of this, he vows to protect her and bring her back to life. In order to do this, however, He must meet many people and go through many challenges.

It is later revealed she is the sister of Hydra Bell and the daughter of Neyn.

Techniques
Franken Stein speculates that due to her nature as a ghost, she will become a very powerful hybrid because she has the ability to absorb and utilize multiple types of magic from other demons, though it requires her to have a source to 'feed' off of, such as Staz's blood. Because of this, he believes that Fuyumi will eventually become powerful enough to rival Staz.

Weakness
Fuyumi's ghost body is, as Staz Charlie Blood explained, an inefficient vessel to hold a tremendous power from Staz' himself, thus resulting for her body to become tired and slowly disappears starting from her limbs. However, if she doesn't acquire Staz' blood to replenish her "mana", she won't be able to live in the demon world and her existence might completely be erased.