Yuuichi Takawashi, a 175 cm tall high school senior with black hair, dark eyes, and a lean 62 kg frame, balances his Taurus practicality with a love for hiking. His younger sister Nagisa’s obsessive affection—marked by persistent romantic fantasies and physical overtures—meets his resolute refusal to cross familial boundaries, grounded in his rigid view of social morality.

Romantic entanglements complicate his life further: a past relationship with Yoko Kishi lingers, while his growing attraction to Kanami Shiomiya, girlfriend of his friend Kotaro Takidani, strains loyalties. A secret sexual encounter with Kotaro results in her pregnancy, though the nature of their current connection remains undefined. Dreams or hypothetical scenarios blur his interactions with the school doctor, adding layers of uncertainty.

Amid post-graduation indecision, Yuuichi grapples with conflicting desires and ethical lines. Nagisa’s fixation and his own wavering impulses fuel a tense emotional landscape, where societal expectations clash with personal longing. Though conscious of consequences, his choices oscillate between restraint and ambiguity, leaving motives deliberately opaque.