Shū Hagiwara, a 32-year-old researcher at an elite university, once taught high school science, crossing paths with a withdrawn Hina Tachibana during her teens. To alleviate her loneliness, he employed puppetry and ventriloquism, forging a bond that matured into friendship and eventual romance after she entered college.

Bound by obligation in a marriage to his mentor’s daughter, Shū endured a union strained by his spouse’s dominance, driving him into a clandestine two-year affair with Hina. Paralysis over finalizing their divorce prolonged the entanglement, intensifying friction as Hina’s stepbrother, Natsuo Fujii—a former pupil—developed rival affections. Shū reluctantly permitted Hina to decide their futures, though his wavering deepened relational fractures.

Post-divorce, he reunited with Hina following her move to Izu Oshima, though the contours of their renewed dynamic remain ambiguous. Physically, Shū cuts a polished figure with wavy, ash-blond hair, sharp blue eyes, and glasses framing a genteel presence. His demeanor blends warmth and introspection, punctuated by playful ventriloquism displays. Yet his chronic hesitancy and deference to social conventions over self-fulfillment expose a man torn between duty and desire.

Botanical symbolism infuses his name: “Shū” (柊) evokes holly olive, while “Hagiwara” (萩原) merges bush clover and field. Though motivated by a wish to flee marital discontent, his prolonged infidelity and delayed resolution seeded ethical quandaries, rippling consequences across Hina and Natsuo’s lives.