K is an introverted elementary school teacher living in Tokyo. He keeps a safe distance from most people, preferring the stability of books and music to unpredictable social interactions. His most significant connection is with his college friend Sumire, for whom he harbors an intense but unrequited romantic and physical attraction. He strives to manage these feelings while maintaining their deeply valued friendship.

Sumire is a 22-year-old aspiring novelist who dropped out of university to pursue writing. She lives a chaotic, disorganized lifestyle, caring little for her appearance or domestic upkeep as she pours all her energy into fragmented fiction drafts. Her routine changes abruptly when she meets Miu and experiences romantic love for the first time, leading her to temporarily abandon writing to work for Miu's international trading company.

Miu is an elegant, sophisticated businesswoman who runs an international trading company specializing in wine. Originally a talented music student studying in Europe, a past incident prompted her to abandon the piano, return to Japan, and take over her late father's business. She exudes confidence and worldly charm, immediately recognizing Sumire's talent and offering her a job as a secretary to help her gain life experience.

K's Girlfriend is the mother of one of K's students. She engages in a secret affair with K, seeking connection to escape the monotony and isolation of her daily life. She frequently feels invisible to her husband and friends, relying on K for emotional support that he is often too preoccupied to fully provide.

Carrot is an elementary school student in K's class and the son of K's girlfriend. He is a quiet, introverted boy who struggles to connect with his peers and exhibits a profound sense of emotional detachment. His shoplifting habit draws K into a closer examination of the boy's silent distress.

Ferdinando is an older man who frequents a local café in a small Swiss town where a younger Miu spends a summer. He develops an interest in Miu that makes her increasingly uncomfortable, contributing to a growing sense of unease during her stay in Europe.