The mouth is typically drawn with an exaggerated "V" or "W" shape, stretching across the face to convey intense emotion.

It is the definition of "bittersweet." The combination of classical piano (Chopin, Beethoven) with the tragedy of a pianist who can no longer hear the music is devastating.

If you have never watched anime before, these series are designed to hook you. They minimize "weird" cultural barriers while maximizing action, drama, and heart.