This book is a fictional telling of story of the expatriate community in Hong Kong during WWII and the social tensions following the war caused by resentment of those suspected of various degrees of collaboration. Racial prejudice between those of Chinese and European ancestry is also described. The Piano Teacher referred to by the title is a hapless new comer to the post war community who stumbles into this maze of past histories. It turns out that war was hell for civilians too. We learn that the scarcity of food and oppressive administration of the occupying Japanese army brought out the best and worst in people. There's a mystery solved in the story, but the reader doesn't learn that there's a mystery needing to be solved until late in the story.
This particular piano teacher gives the profession a bad name. Her bad behavior allows the story to move forward, but it has little to do with teaching piano. The reader doesn't learn much about teaching piano from this book.