Jill is a young, brown-haired girl with two pigtails that reach her shoulder blades. She is short in stature, her height reaching slightly above Guts' waist, and her clothing befits that of a peasant. Her eyes are wide and blue, and a shawl is draped over her shoulders, tied in a ribbon at her chest. Similarly, she wears a small piece of fabric around her waist which is also tied in a ribbon, though at the back rather than front. Ruffled at the sleeve ends, the majority of her dress is light in color; the laced section above her hips is of a darker shade. Her shoes are simple, covering up to her ankles.
Despite being sensitive, Jill is not afraid to voice her opinion. Her father Zepek, a reminiscent drunk fixated on the memory of his former military days, is abusive towards her, crudely hitting his daughter and leaving her starved for affection. As a result, the two often get into arguments. While her mother is more caring and compassionate, she too suffers from her husband's neglect; Jill's household is a "battlefield", broken and dysfunctional, and Jill herself is profoundly unhappy. She is not shown to have any friends to confide in.
However, for some time in the years leading up to her meeting with Guts, Jill had a best friend in the form of Rosine. As an only child, Jill considered Rosine to be like a real big sister, the latter being four years older than her. But, despite their close bond, Jill thought her friend's boyish antics to be strange and failed to realize that she was abused by her father, much like Jill herself would be in later years. Following the sudden disappearance of Rosine, Jill is left alone to reflect upon their relationship. When the two finally reunite and the now apostle offers Jill the opportunity to become an elf of the Misty Valley,  the young girl declines after seeing the true nature of the so-called elves' "paradise". Nevertheless, Jill still considers Rosine to be her closest friend, reaffirming her belief in elves  and shielding the fatally wounded apostle from Guts with her own body as he prepares to finish her off.
Frightened of her true parent, and having been saved by the swordsman from bandits and apostles alike upon their initial encounter, Jill finds a new father figure in Guts during their short time together, a relationship Rosine suspects to be a crush on the young girl's part. Childishly referring to him as "Mister Swordsman", Jill is considerate towards Guts, bringing him food after he is ran out of her village on account of the elf in his company. She also expresses a desire to follow him, first to find Rosine,  and then to get away from her village. However, the swordsman refuses her final request, knowing that to bring her along would put her life at risk, and imparts with her the assurance that she must fight on her own "battlefield". Jill takes this advice to heart, returning to her village with a newfound sense of hope.