Question: who plays the piano in your lie in april
Answer: 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 .