Who is Ji Shen from Women of the Silk and what is their importance?

Ji Shen arrived at the girls' house unexpectedly. Her family was attacked and murdered by Japanese soldiers. Following the assault, she ran south as far as her legs would carry her. She traveled without food and shelter for many days before collapsing on the doorstep of the girls' house. She was malnourished, dehydrated, and the sores on her feet had become infected. Additionally, she and her mother and sister had been sexually assaulted by the soldiers.