Shino Hizuki belongs to the Hizuki family as the older sister of Ayumi and Mitsuna Hizuki. She teaches at Akizuki Academy, where her youth and gender attract student popularity despite her confessed lack of special passion for the profession.

Her appearance features long black hair and violet eyes. She dresses in professional attire like blazers, jackets, trousers, and traditional hakama, alongside personal garments such as miniskirts and lace lingerie. She wields a black belt in aikido, gained during her schooldays for self-defense.

Shino speaks directly and harshly, adopting a fiercely protective stance toward her younger sisters. She openly opposes Naoto Rindo's presence in their household and his goal of impregnating a Hizuki sister to break a family curse. She battles excessive alcohol consumption, frequently suffering memory loss from overindulgence.

A past failure or trauma involving men caused her to suspend romantic relationships, though specifics remain undisclosed. This fuels her defensive approach to male interactions and prioritization of shielding her sisters. She is noted as not a virgin but currently has no romantic involvements.

Within the series, her role shifts between installments. The original narrative positions her as a potential participant in Naoto's involvement with the sisters. In the sequel *Shin Ringetsu*, she appears but refrains from sexual activity as the story centers on Ayumi and Suzune. Her protective instincts toward her sisters remain unwavering across both narratives, consistently emphasizing her responsibility for their welfare.