Serena Ijiyuuin is the second daughter of the Ijiyuuin household. Her father employs Yuuto Akiyama, a young man working to atone for his father's alleged misdeeds. Serena possesses a thin yet busty, voluptuous figure, noted by sources, with distinct pink hair and red eyes. Her personality is generally happy and cheerful, but she exhibits quick shifts to anger and spitefulness, holding grudges for extended periods. Jealousy surfaces when others interact romantically with Yuuto before she gets the opportunity.

As a vampire, Serena faces the inherent limitation that her partners typically do not survive beyond one day after intimacy. This trait defines her interactions and romantic pursuits. She actively utilizes her physical attributes to entice and seduce Yuuto. Her efforts to initiate a relationship with him encounter repeated setbacks due to prior encounters between Yuuto and other characters, including the household maid Mizuki and a figure known as Sister. These interruptions fuel her jealousy and frustration.

Within the household, Serena maintains familial relationships, including with her older sister Marie Ijiyuuin. The sisters coexist alongside other non-vampire residents: Mizuki, a demon serving as the household maid, and Sister, a human associated with their school. A significant narrative revelation confirms Yuuto's hidden heritage as the son of the vampire king. Serena's father initially suspects Yuuto's lineage, perceiving him as the offspring of a traitor; these doubts subside only after a specific confrontation. The discovery of Yuuto's royal vampire lineage occurs in Serena's presence, alongside other household members including Sister.