Your lie in April: Moments Shigatsu wa Kimi no Uso: MOMENTS English Subbed

OVA bundled with the 11th Shigatsu wa Kimi no Uso manga volume.

The OVA focuses on Kousei, Emi and Takeshi when they were younger, showing their troubles during their competitions and the beginning of their rivalry.

(Source: Shigatsu wa Kimi no Uso Wikia)