Marina Akizuki is a high school student and the elder daughter of Kayoko Akizuki, with a younger sister named Airi. Her stepfather is Kouzou Akizuki, who married her mother. Marina has a French biological father, though he remains otherwise unspecified. She possesses long brown hair, typically parted to the side and reaching her waist or beyond, violet eyes, a slim build, and a pale complexion. Kind by nature, Marina enjoys pastimes such as cooking. Her position in the Akizuki household is that of an older sister and stepdaughter to Kouzou, a teacher and pharmaceutical researcher whose obsessive attraction toward Marina and Airi complicates their family life. He employs an experimental estrus spray to induce non-consensual sexual encounters, and Marina becomes a primary target of this substance. In the original visual novel, Kouzou’s actions are partly motivated by concern over Marina’s virginity and another individual named Masato. Adaptations such as the OVA present variations in the family’s reactions, at times depicting more confrontational or explicit scenarios. Marina’s relationship with Airi is explored through different narrative contexts. In certain paths, including an unlockable harem route, they engage in sexual acts with their stepfather. One such instance involves Marina receiving oral sex from Kouzou while Airi uses a strap-on from behind. The OVA adaptation also shows the sisters competing for their stepfather’s attention under the influence of the spray. The character appears in further game content like “Oni Chichi After 2,” where additional testing of the aphrodisiac spray takes place. Marina is often depicted in a school uniform, knee-high or thigh-high socks, a choker, a maid dress with headdress, loafers, pajamas, lingerie, and similar attire.