Kuro embodies the peculiar fusion of vampire and feline nature, standing tall and elegant at six feet with an aristocratic bearing that betrays his supernatural origins. His jet-black hair falls in silky strands around a face that maintains a delicate balance between human and feline features - high cheekbones, slightly elongated amber eyes with vertical pupils that dilate in darkness, and unusually sharp canines that he carefully conceals when speaking.

His most striking characteristic is the way he unconsciously displays his dual nature, even in human form. Despite his sophisticated appearance, typically dressed in well-tailored Victorian-style clothing in dark colors, Kuro often finds himself unconsciously responding to head pats or scratches with a distinctly feline purr. These moments of vulnerability contrast sharply with his otherwise composed demeanor, creating an endearing dichotomy that he struggles to reconcile.

The vampire-cat's relationship with his 'owner' Mahiru is complex and fascinating. While his supernatural powers and immortal nature should place him in a position of dominance, Kuro's feline aspects create an unusual dynamic where he craves the attention and affection typically given to a beloved pet. This internal conflict between his proud vampire nature and his instinctive feline desires creates a constant source of embarrassment and frustration for him.

Kuro possesses the ability to transform into a sleek black cat at will, a form he often uses when he needs to observe without drawing attention or when his feline instincts become overwhelming. In this form, his vampire nature becomes secondary, though his intelligence and awareness remain unchanged. The transformation is seamless, accompanied by a subtle shimmer of dark energy that dissipates like smoke.

Despite his considerable powers, Kuro battles with a profound sense of ennui that comes from centuries of existence. He often appears lazy and unmotivated, preferring to curl up in a patch of sunlight (which, unusually for a vampire, doesn't harm him) rather than engage in the dramatic conflicts typical of his kind. This apparent apathy masks a deeper fear of attachment and loss, born from countless cycles of forming bonds with mortals only to watch them fade away.

His speech patterns are distinctive, often punctuated with sighs and cat-like vocalizations that he can't quite suppress. When agitated or excited, his speech becomes more feline, with occasional 'nya' sounds slipping into his words, much to his mortification. This involuntary behavior serves as a constant reminder of his unique dual nature and adds to his complex character.