Itoko no Onee-chan ni Amaechau?

As Masato Ooizumi steps through the threshold of his new temporary home, he carries the usual anxieties of a freshly minted high school student—uncertain friendships, academic pressures, and the daunting weight of adolescence. Yet his worries take an unexpected turn when he discovers that his host is no distant relative, but his older cousin, a young woman whose warmth quickly blurs the boundaries of familial decorum. What begins as a simple arrangement for convenience soon becomes a daily trial of composure, as her affectionate gestures and unabashed closeness leave Masato perpetually flustered, struggling to navigate the delicate line between gratitude and the confusing stirrings of something deeper. Within the quiet walls of their shared household, the ordinary rhythms of life—morning greetings, shared meals, and quiet evenings—are charged with an unspoken tension that Masato can neither ignore nor fully understand. His cousin’s radiant smile and playful teasing seem effortless, yet each encounter chips away at his carefully maintained reserve, forcing him to question whether her attention is merely the doting nature of an older sibling or a deliberate invitation to something far more intimate. As he grapples with his own rapidly evolving emotions, Masato finds himself caught between the safety of family bonds and the exhilarating, terrifying prospect of a romance that society might deem forbidden, all while trying to keep his fledgling high school life from unraveling at the seams.