In early 20th century London, a young Japanese woman named Lili Ichijoin arrives to enroll at the prestigious Saint Thomas Art Academy, determined to become a professional painter. She carries a heavy ultimatum from her mother: she has only six months to become the top student in her class, or she must abandon her artistic ambitions forever and return to Japan to inherit the family's kimono business and enter an arranged marriage.

Upon her arrival, Lili crosses paths with Kit Church, a mysterious and scruffy aristocratic student who consistently ranks first in all his assignments. Known for his singular devotion to art and his emotionally distant nature, Kit is the younger son of a duke, a fact he keeps hidden from most of his peers. What initially forms between them is a sharp rivalry, driven by Lili's desperate need to succeed and Kit's detached brilliance. However, as Lili's sincerity and perseverance begin to challenge Kit's isolated worldview, their competitive relationship gradually deepens into a complex romance, intertwining personal growth with their shared pursuit of artistic excellence.

Lili's new life at the academy introduces her to a circle of friends who shape her journey. She finds a loyal confidante in Dorothy Brown, her friendly English housemate from the Cotswolds. Another Japanese student, the sculptor Shinnosuke "Shin" Kobayakawa, moves in across the street with his mute younger sister Sakura, and Shin develops an unrequited love for Lili. She also becomes entangled with the academy's demanding oil painting professor, Charles Brant, and Kit's aristocratic circle, including his friend Joffrey O'Brien and Peter Anthony, an artist from Delhi. Adding to the social tension is Catherine Astor, Kit's aristocratic fiancée, who eventually befriends Lili and chooses to break off her engagement to pursue her own path as a dressmaker.

The story's narrative arcs follow Lili as she navigates the pressures of the academy, including competitive exhibitions at the National Gallery and harsh critiques of her work. A significant arc involves a holiday visit to Kit's vast family estate, Drunnheim Hall, where Lili witnesses the immense pressure Kit faces from his older brother, Richard, to accept his aristocratic duties. Upon returning to London, a period of financial hardship forces Lili to take on translation work and a portrait commission from Catherine, which leads to moments of self-discovery and a growing friendship between the two women. As whispers of World War I begin to surface, Kit withdraws from the academy to serve as an ambassador and to attend to his dying father, leaving Lili to confront her feelings alone.

Five years later, with the war having passed and believing Kit to be dead, Lili has given up painting entirely and is engaged to Shin in Yokohama. However, a chance sighting of a painting that resembles Kit's work reignites her passion. She and Shin track down a lost and changed Kit, leading to a final resolution where Lili and Shin break off their engagement to pursue their respective artistic dreams, as Kit returns to his life in England, leaving their future together an open question.