America: My Nephew Mozart, the Six-Fingered Piano Demon

My name is Zheng Zhuan. I went to New York to find my nephew Mozart, who was majoring in piano. I found that he only had six fingers left on his hand, and I laughed at myself as a six-fingered piano demon. Why did I awaken the Six Finger Piano Demon System? And it calls me a knight? No matter what, I want to find the murderer of my nephew... [Welcome to the world of martial arts, the six-finger piano demon, improve your skills] [You have received a mission: find the murderer of Mozart] [Six-finger piano demon, sixth finger, exclusive skill] [Eight Dragons Tianyin, Chapter 1: Mourning Sound] Who is the Six-fingered Piano Demon?