Hanasaki Horie, father to Ao Horie, is a celebrated erotic novelist responsible for bestsellers like "Promiscuous Lament" and "100 Words of Significance in Bed." His profession warps Ao’s view of men and sexuality, driving her toward academic obsession and plans for distant university enrollment to flee his influence. When Ao catches classmate Takumi Kijima’s romantic attention, Hanasaki invades her personal life—his actions oscillating between misguided support for her emotional growth and boundary-crossing meddling. He dispenses advice to foster her relationship with Takumi, yet his tactics muddle parental concern with intrusiveness.

Physically, he presents a small frame, balding white hair, black eyes, and facial stubble. Professionally, he adopts pen names like "Kairaku-sensei" (Pleasure Teacher) and "Floral Hori." His parenting philosophy rejects strict oversight, aiming to rectify his own parents' flaws, but inadvertently feeds Ao’s insecurity and isolation as she mistakes his leniency for neglect.

During Ao and Takumi’s interactions, Hanasaki shifts from comedic disruption to earnest guidance, embodying a contradiction: his novels fuel Ao’s anxieties while he urges her toward romantic openness. This duality frames him as both instigator of her turmoil and flawed paternal figure.

He persists in the sequel "Ao-chan Can't Study: Otona-hen," where his core traits—author persona, parenting inconsistencies, and physical depiction—remain unchanged.