Hitomi Kisugi is the middle daughter of art collector Michael Heinz and a Japanese mother, resulting in her mixed German-Japanese heritage. During childhood, she displayed European features such as blonde hair that later darkened to black, now maintained with occasional dyed blonde strands. Her father's disappearance in her youth—initially presumed to be his death in a fire—compelled Hitomi and sisters Rui and Ai to lead double lives: operating the "Cat's Eye" café by day while functioning as phantom thieves by night. Their core mission involves retrieving stolen artworks created by their father, which conceal clues to his fate. They announce heists through calling cards to draw his attention.

As the Cat's Eye team's primary operative, Hitomi executes most heists. She deploys exceptional athleticism, acrobatic agility, and martial arts mastery across judo, boxing, karate, kendo, and aikido. Additional skills include safe cracking, horseback riding, driving cars and motorcycles, and effortlessly escaping restraints. Ambidextrous and double-jointed, she shares her sisters' expertise in disguise, multilingual linguistics, and latex mask impersonations. Tactically, she creates distractions, traverses rooftops, and utilizes gadgets designed by Ai, frequently undertaking solo missions. She rejects firearms, favoring non-lethal metallic calling cards as thrown projectiles.

Her personality merges kindness and fierce loyalty to family with a volatile temper, particularly toward fiancé Toshio Utsumi, a police detective. She routinely clashes with him over his interactions with other women, especially investigator Mitsuko Asatani, revealing intense jealousy. Despite conflicts, she deeply cares for Toshio and eventually discloses her Cat's Eye identity before fleeing. After Toshio resigns to pursue her, she contracts amnesia from viral meningitis, though their relationship later mends. This dynamic anchors her emotionally between sisters Rui (strategist) and Ai (tech specialist).

In the crossover "Lupin the 3rd vs. Cat's Eye," Hitomi shifts to a support role while Ai leads. The sisters pursue three paternal paintings hiding "Stones of Fortuna." Misinformed by antagonist Heinrich Berger—who falsely accuses Lupin of betraying their father—they initially battle Lupin's gang. Despite reduced prominence, Hitomi engages in critical heists, including a train operation where she employs disguises and combat against Berger's forces. The conflict resolves with the sisters reclaiming the paintings and exposing Berger's deception, while Lupin's gang departs unrewarded.