Does Hua Mulan disguising herself as a man to replace her father’s military duty mean she fulfilled filial piety? The equality between man and woman is not a modern idea, but already happened a long time ago (Mulan’s story was written in the 6th century). But how could she not be recognized during her 12-year army service? Did she look really ugly? We try to use the 21st-century view to work about what on earth happened to her at that time.