Kazuko Kuhōin is a central figure in her narrative, introduced as the young heiress of the Kuhōin family, one of the most powerful financial conglomerates in the world. She is a girl of only seven years old, yet she is thrust into a world far removed from the sheltered existence typical of someone her age. Her background is marked by a dark and complex family secret. While publicly acknowledged as the daughter of the Kuhōin family head, Renjō Kuhōin, and his wife, the truth is far more scandalous. She is actually the child born from an incestuous relationship between Renjō and his own younger sister. This disturbing reality is directly tied to a genetic defect within the Kuhōin bloodline, which forces them to produce offspring only through close relatives. Because of this, all women born into the family are destined to spend their entire lives confined within a secluded facility known as the Satoin.

Her personality is a striking blend of innocence and precocious intensity. Due to the strict and unnatural educational policies of the Satoin, Kazuko severely lacks basic common knowledge about the everyday world. She is, however, a deeply curious and inquisitive child, always eager to learn new things, which often leads her to ask direct questions about topics far too advanced for a girl her age. This curiosity is driven by a simple, powerful wish she harbors: to experience romantic love. It was this wish that motivated her mother’s friend, Kurenai Benika, to break her out of the Satoin, setting the story in motion. Beneath her childish exterior lies a sharp and almost unsettling perceptiveness; she possesses the remarkable ability to see through any lie and can be quite formidable when opposed, displaying a terrifying presence that belies her years.

In the story, Kazuko’s primary role is that of a protected charge. After being taken from the family estate, she is placed under the care and protection of the young high school student and dispute mediator, Shinkurō Kurenai. Their relationship is the core of the narrative, as she moves into his apartment and begins a strange, cohabitative life with him. Her role evolves from a simple mission target into the emotional heart of the story, representing not only Shinkurō’s responsibility but also his personal connection to a world beyond his violent duties. Her key relationships are central to her development. Her bond with Shinkurō deepens as she comes to trust him completely, eventually developing a childish but genuine romantic attachment to him, even going so far as to give him her first kiss. This relationship creates other significant dynamics, most notably a rivalry with Yūno Hōzuki, the heir to the Hōzuki-style martial arts, who is also fond of Shinkurō. Her relationship with her birth father, Renjō, is complex, defined by the oppressive and unnatural rules of her family, while her connection to Kurenai Benika is that of a savior who fulfilled her mother’s wish. Kazuko’s development throughout the story is one of gradual adaptation. She slowly learns about the normal world and, more importantly, learns to form genuine human connections. Her motivations remain tied to her initial desire for love and freedom, which she begins to find in her new, chaotic life with Shinkurō. Regarding any notable special abilities, aside from her aforementioned and highly acute ability to detect falsehoods, she has no combat or supernatural powers typically seen in the series’ world of underworld families. Her strengths are her perceptiveness and her fierce, unyielding will.