Piano prodigy Kōsei Arima dominated the competition and has become famous among child musicians but also controversial. After his mother, who was also his coldhearted, abusive instructor that forced him to play the piano emotionlessly, died, he had a mental breakdown while performing at a piano recital at the age of twelve. As a result, he is no longer able to hear the sound of his piano even though his hearing is perfectly fine. Two years later, Kōsei hasn't touched the piano and views the world in monochrome, without any flair or color. He has resigned himself to living out his life with his good friends, Tsubaki and Watari, until, one day, a girl changes everything. Kaori Miyazono, a fourteen-year old audacious, free-spirited violinist whose playing style reflects her manic personality, helps Kōsei return to the music world and shows that it should be free and mold breaking unlike the structured and rigid style Kōsei was used to, and as she continues to uplift him, he quickly realizes that he loves her.