Your Lie In April,Kōsei Arima

Kōsei Arima (有馬 公生 Arima Kōsei)

Voiced by: Natsuki Hanae (Japanese); Max Mittelman (English) & Piano performance by: Tomoki Sakata

Played by: Kento Yamazaki (live-action film); Shintarō Anzai (stage play)

Kōsei is a former child prodigy in playing piano, dubbed the "Human Metronome" for his near-inhuman mechanical accuracy, a product of his mother's overly strict methods of teaching. His ability to play the piano with unparalleled precision led him to win many competitions across Japan and even be invited to play abroad. When his mother died, the resulting psychological trauma caused him to be unable to hear the sound of his piano playing, and he gave up on it. Two years later, he takes up the piano again after being convinced by Kaori Miyazono to become her accompanist. Influenced by her emotional and unrestrained playing style, Kōsei eventually finds himself falling in love with her. He, however, does not confess his feelings due to her liking his best friend, Ryota Watari.

It is later revealed in Shigatsu wa Kimi no Uso: Coda, a side story from Kōsei and Tsubaki's childhood, that his inspiration for playing so beautifully in his first competition was to cheer up Tsubaki after the passing of her grandmother.