It's inspired by the true story of a Chinese-African Cuban girl, Millo Castro Zaldarriaga, from 1932. The story is that a girl wants to play the drums, but where she lives, people believe that only boys should play drums. So she dreams about it and listens to the music and imagines herself playing music for a long time, and then eventually she just decides she's gonna play the drums and she plays them.
Message
Don't give up on your dreams just because people say that they're unreasonable.