My Sister's Friend: The Onii-san Who's Only Mine
Utai Suzu
She's your little sister's friend—a sweet, playful girl who calls you 'onii-san' with easy familiarity through games, phone calls, and morning wake-up calls. At first her affection looks like harmless teasing, but it slowly reveals an obsessive, unsettling edge. Part of the 'Yandari' series, this work traces the moment sweet romance tips into psychological horror.
