In her Magic-User form, she appears as a slim young woman with short black hair and black leather clothing. In her devil form, she takes on the appearance of some form of antlered, furry monster covered in winter's jackets and scarves, though with two glowing eyes shining through. Upon closer examination of her face, we see a much more sinister skull-like design.
As the average devil, Haru takes up a care-free personality and rather apathetic traits towards everybody, though she does show some empathy towards her husband, Kasukabe. She generally seems to just care about her own needs and especially her music, often practicing her singing since she's in a band with a bunch of devils and Chidaruma.
Despite being a devil, Haru is shown to still care for her husband as she visits him often and shows concern for him. She hid him inside devil body to avoid his detection from the other devils in the supermarket. After he was accidentally killed by her devil body while she was fighting a half-devil Nikaido, she grew enraged and lost all rational thought.
A young Haru was found during a rainy night in Hole by the recent graduate Prof. Kasukabe (known as Haze back then). It is unknown how much time passed until they got married, and Vaux said that he barely remembers a young woman with Kasukabe during his years as his student. 25 years prior to the series' events, she departed to the Magic User realm once again to live in a small cabin in the Hydra Forest. She took the Devil exam and passed, with time becoming well known as one of the Devils who mostly hang out with Chidaruma. Seeing as he gave her the Store's kitchen knife, Chidaruma apparently either trusts her enough to do what she pleases with it or just doesn't care at all who uses it.
Living a carefree life over the years, she returned to her old home to find a child looking Kasukabe. They spend some time having a warm catch-up after her husband gave her old bracelet as a gift.
She tagged along with Duston, Moroku, GuraGura and Chidaruma to an improvised party in Hell to celebrate the new year, where she used the Store's kitchen knife to cut the meat and bread for the party. Duston was really terrified of the Knife.
- Loves to sing and make music, but is tone-deaf
- Writes strange gory/dark songs all the time (especially at the worst times)