Nagisa Kashiwagi, a second-year student in Shuchi’in Academy’s Class 2-B, presides over the Volunteering Club while bearing the legacy of her influential family—her father chairs a major shipbuilding conglomerate, and her grandfather directs the Japan Federation of Economic Organizations, securing her position among the academy’s elite. Academically formidable, she consistently ranks within the top ten of her class.

Her romance with classmate Tsubasa Tanuma ignites after his confession, tactically guided by Miyuki Shirogane’s "wall-down" advice. What begins as a whimsical acceptance evolves into a stormy high school relationship, marked by jealous extremes like hiring a private investigator to track Tsubasa. Conflicts frequently melt into passionate reconciliations underscored by uninhibited physical affection. Nagisa regularly exchanges romantic counsel with Kaguya Shinomiya, forging a mutual mentorship that thrives on shared curiosity and whispered gossip, despite Kaguya’s initial inexperience.

A turning point emerges when Nagisa confides in Kaguya about her escalating intimacy with Tsubasa—their first sexual encounter occurring two months after their initial kiss, accelerating swiftly following their first French kiss. Three months into their relationship, an unplanned pregnancy irrevocably shifts her story’s course.

Nagisa’s short dark brown hair frames a face accentuated by a double-banded left-side hairpin, her dark brown eyes complementing Shuchi’in’s standard uniform. She maintains close ties with Maki Shijo and Kaguya, deftly navigating their personal trials alongside academic pressures and her own entangled responsibilities.