Aya Shirakaba is a 16-year-old high school student with aubergine hair often in a ponytail and grey eyes. Her father, a wealthy and powerful yakuza boss, relocates her to live with Tairaku, her teacher, charging him with ensuring her safety and chastity under threat of severe consequences. She first meets Tairaku when he finds her smoking on the street and lectures her. Following this, she develops an intense fixation on him. Her precise motivations remain ambiguous; some actions suggest genuine affection, while others appear calculated to provoke discomfort. She initiates a kiss during their initial encounter, later accusing him of stealing her first kiss despite her aggressive approach. After transferring into Tairaku's class, she moves into his apartment at her father's direction. She frequently exhibits provocative behavior in their shared space, such as lounging scantily clad or appearing partially unclothed, creating significant tension for Tairaku, who must resist her advances to avoid her father's wrath. Her presence attracts unwanted attention from male and female peers at school, forcing Tairaku to intervene against inappropriate contact. Despite her overt actions, she maintains an outward appearance of innocence and purity, leveraging this perception to manipulate situations. Her cleverness contrasts with Tairaku's restraint, and she demonstrates a tendency to place him in compromising positions, though whether this stems from emotional attachment or a desire to unsettle him remains unclear.