Hiroaki is Reiko's husband, exhibiting a pronounced fixation on idol Mamayu due to her physical resemblance to his wife. This obsession directly impacts their marriage, requiring Reiko to role-play as Mamayu during sexual encounters where he exclusively vocalizes the idol's name, disregarding Reiko's identity and emotional needs. His preoccupation creates significant sexual dissatisfaction for Reiko, contributing to marital strain. During a celebratory dinner with his friend Taniguchi, Hiroaki drinks to unconsciousness, leaving Reiko alone with Taniguchi without his awareness or intervention. After Reiko's subsequent sexual involvement with Taniguchi, the marriage persists but undergoes a substantial shift: Reiko continues extramarital encounters to fulfill unmet needs while Hiroaki persists in his idol role-play demands during intimacy, remaining seemingly unaware of her affair. His characterization shows no evolution beyond this pattern of behavior.