Kōya Asumi is a diligent fourth-year college student working part-time as a housekeeper for Keiichi Naruse, a single father. His prior experience caring for his nephew fosters an easy rapport with Keiichi's young son, Ichika. Independent living has honed his domestic skills, especially in cooking and household management, which he applies effectively in his role.

Initially identifying as heterosexual, Kōya develops an unexpected attraction to Keiichi, drawn by his physical appearance and gentle nature. This intensifies after he discovers Keiichi's adult materials during cleaning, prompting Kōya to initiate a kiss and offer assistance with his employer's sexual needs. He frequently grapples with internal conflict over his feelings and the propriety of his advances but persists in pursuing Keiichi.

Kōya navigates the relationship's complexities, addressing Keiichi's reservations from past housekeeper experiences. He evolves from a task-focused employee to an emotionally invested partner seeking authentic romance beyond their professional dynamic. His commitment strengthens, culminating in a mutual decision to build a family life together with Ichika.

Physically, Kōya has black hair, grey eyes, stands 1.78 meters tall, and holds blood type A. Born on May 21 with Japanese nationality, his personality combines responsibility, straightforward expression of desires, and persistent emotional and domestic support for Keiichi. His affectionate bond with Ichika reflects inherent comfort with children.