Kousei Arima, known as the "Human Metronome" for his impeccable piano performances, was molded by rigorous maternal discipline and exhaustive training. He dominated every competition he participated in, earning the respect of his peers and the admiration of audiences. Yet, the abrupt death of his mother triggered a trauma that left him unable to hear the piano's sound, causing him to cease performing.
Currently, Kousei lives a quiet life as a middle school student alongside his friends Tsubaki Sawabe and Ryouta Watari. Struggling with the loss of his mother and his attachment to music, his world remains bleak. This changes when he encounters the free-spirited violinist Kaori Miyazono, who draws him back into the world of music as her accompanist. Through a minor ruse, they grow closer, and Kaori strives to bring color back into Kousei's monochromatic life.