Hilda is an attractive young woman with blonde hair that covers one side of her face and is tied in a bun, green eyes and a well endowed chest. Her clothes are mostly elegant and black with frills and white quillings, thus resembling Lolita Fashion. She is seen wearing other outfits on a few occasions. One occasion being right after she wakes up, where she was wearing a modest pink night gown with her hair down.
When she infiltrates Oga’s current school she dresses in the Saint Ishiyama High uniform, though she complains that the shirt is “a little tight.”
Hilda commonly displays a cold and impassive demeanor, a character trait that she breaks only on rare occasions. (excluding her interactions with Be’el). Toward Be’el she is very affectionate and protective, acting as the role of the mother and preforming the task a mother would such as cooking for and washing Be’el. She often knows more about the current situation than any of the other protagonists and is easily able to manipulate the others into doing what she sees best. Hilda also has a fondness for extremely spicy foods, such as super spicy habenero buns.
She is shown to be just as bloodthirsty and violent as Oga, a trait that earned her the nickname “Oga’s Bride” at Ishiyama. In a fight she displays a complete confidence in her own skill and power, regarding her opponents calmly and often taunting them in mid battle.
She enjoys teasing and tormenting Oga, frequently making marks about his intelligence and (in her own mind) poor parenting skills. In the beginning of the series she is openly dissaproving of Oga as Be’el’s parent but after the delinquent defeats Toujou she becomes much more accepting and warmer towards him, even thanking him after. But she still bickers with him.
In Chapter 104, it is hinted that her time with Oga and Baby Beel has changed her, as Izabella noted that her personality has changed since coming to human world and wonders what kind of human is responsible for this change.
Hilda originally came to the human world by command of the Demon King to raise his son, Kaiser de Emperana Beelzebub IV, to be a ‘good’ human destroyer. Beelzebub however got so attached to Oga Tatsumi, that she now observes him and his progress in being the future demon king’s parent.
Despite the fact that she is naturally just as fast as strong she is as a demon, Hilda rides a giant bird-like being named Ak-Baba. Although she has not been shown riding it lately.
She is known to had an alter ego, which is a more ladylike version than her normal appearance, softer and cares more towards Oga Tatsumi (believing that she is his real wife), and also a better cook. This was a result of one of the pillars of bahemoth trying to make her a nurse for lord en by erasing her memories. However, she returned to her normal personality after she kissed beelzebub.
After awhile, the “softer” version of hilda appears again. And it is known that the kiss with beelzebub is the switch to her personality changes.