It's the Age of Steam, but I Was Possessed by a Supernatural Being at the Beginning

"I am Cassian Holmes. When you read this, you will be dead..." Golden lettering floats over the piano. A blond man sits at the piano. His fingers fell on the black and white keys. The piano sounded. The yellowed sheet of music was spread out on the piano stand, and as he played, notes emerged one after another. Play the "supernatural" music.