Who is An-Yi from Red Scarf Girl: A Memoir of the Cultural Revolution and what is their importance?

An-Yi is the best friend of Ji-li. They have known each other since they were babies. An-Yi is in the same school class as Ji-li and experiences some of the same difficulties as Ji-li does. She also finds it difficult to write posters criticizing her teachers. Since Ji-li is her best friend, she often sides with her in discussions with other students. It is An-Yi who tells Ji-li that her name is mentioned in a poster.