TV-Series
Description
Hatsune Arisaka lives next door to the Kagura family as the older sister of Kazuki Arisaka. With their parents stranded overseas, she takes charge of her younger sister and the Kagura siblings, Yuuji and Marie, managing household duties and offering support, though she fiercely rejects any "motherly" label. She possesses a curvaceous figure and notable bust size, attracting admirers including Yuuji, who generally respects her boundaries. Her appearance features blonde hair in manga and brown hair in anime.

Her personality mixes mischievous teasing with genuine care. She actively engineers romantic scenarios between Kazuki and Yuuji for her amusement, creating embarrassing situations, tying up Marie to prevent interference, and recruiting Kazuki's friend Chihaya as a lookout. She frequently dons cosplay at home, sometimes unsettling others. Beneath this playful exterior lies deep loyalty, especially toward Kazuki; any hint of Kazuki's illness triggers exaggerated anxiety, making Hatsune clumsy and frantic until reassured. She comforts Marie during struggles with Yuuji's changing relationships. Her competence shines in academics, sports, and cooking, contrasting with Kazuki's skills.

Key relationships define her interactions: she teases Kazuki relentlessly about Yuuji's attraction to her physique, undermines Marie's attempts to discipline Yuuji, and harbors a potential romantic interest in Kogorou, her former tutor and Kazuki's teacher – an interest he flusteredly returns.

She plays a pivotal role by correcting Kazuki's idealized childhood memories, presenting a forgotten diary that reveals Yuuji's early perverse tendencies and Kazuki's past tolerance, facilitating their reconciliation. In later manga, she continues mediating their relationship while fiercely protecting Kazuki. Her quiet authority is formidable, demonstrated when she prevents Yuuji's photography boss from contacting family during a crisis without raising her voice. While her matchmaking persists, her core dedication to family welfare remains constant.