Yasumi is a half demon, the daughter of the old demon lord. She carries the age of 15 on earth.
Yasumi's father is the old demon lord. Her father made her mother pregnant when he was disguised on earth. Yasumi's mother got murderd by demons just after she gave birth. Yasumi was taken by her father to hell and grew up there. She turned evil because of her father, but deep down she's a good person. When Yasumi was older, her father gave her a quest. She had to look for a strong and powerful body on Earth, one which can stand a big power and damage. Yasumi didn't know why, but she went to Earth and started looking while she was acting to be a normal human. She got a limited period of time and demons were watching her, so she'd do her quest.
When Yasumi was at the age of six, she was forced to bring out her demon, Elatha, but wasn't able to. Her father went really far to get her demon out. Ever since then she had a bad bond with her father and wanted to ruin his plans.
Elatha carries a huge power, for example, she can kill over a 500 shadow creatures by only snapping with her fingers.
Yasumi has turned evil because of her father, who's only a spirit now. She grew up and learn how to be evil, but deep down she doesn't want to be it. She feels it's wrong and she doesn't like to be forced. Yasumi is a lonely girl, because she grew up in an old castle, she never had any friends or family that showed her love or friendship. The demons around her were cruel and didn't care about anything. Elatha wanted to live a normal life ever since she saw some people out of the castle who were laughing and playing together.
Yasumi loves the autumn and around that time she loves to be outside in the forest when she's on earth. She's a shy and doubts a lot about things when she's separated from Elatha. Elatha have a bit of a temper, but she knows how to control it and is a calm girl most of the time. She doesn't get scared easily. In opposite of Yasumi, Elatha is confident and doesn't fear to take decisions quickly.
Yasumi has a warm blond color hair and brown eyes. She loves to wear the color red.
Elatha's demon (/true) form contains long, light purple hair and blue, almost purple, eyes. She has two horns on her head and wears a dark dress. On her back she carries two black wings.
Not only does Yasumi carry a demon inside of her, she has also the real demon powers. These two are different; Elatha has a personality on her own and is like a second person inside of Yasumi. The powers can make Yasumi change in appearance and strenght, only when she loses control her personality changes, which always happens when she releases the powers, which she barely does.
When Yasumi is using these powers, her hair turns long and black and her eyes turn glowing red. Her clothes will change to a white dress and black wings will appear on her back.
Yasumi/Elatha appears in the story about Hiryū's past.