Keiichi Kanejō, an older brother to Kyoka Kanejō and a Harvard Business School student, possesses universal attractiveness. His charm is so potent it ensnared even a foreign princess, making him the subject of widespread female infatuation. Unbeknownst to him, his sister Kyoka maintains an obsessive complex, secretly and systematically removing potential romantic rivals to preserve his virgin status.

Returning to Japan, Keiichi develops a distinct interest specifically in Yamada, captivated because she is the first woman not instantly drawn to him like others. This unique dynamic fuels his curiosity and pursuit. He confirms his virginity when questioned by Yamada, remaining oblivious to his sister's interventions.

Later becoming a guest English teacher at Yamada's school, Keiichi persists in his advances despite her rejections stemming from existing feelings for Kosuda Takashi. His pursuit culminates in a direct confession and proposition to Yamada to lose their virginity together, which she declines. Even after this rejection, he continues his undeterred efforts to engage with her, maintaining his interest without accepting her refusal as final.