How did Jiang Jia and Sue meet?

We are classmates. According to the video of Uniqlo, Jiang Jia and Su are the characters in When I Run to You. Jiang Jia and Sue were classmates when they met. Content excerpt: Sue packed her things and got ready for school. She came to Jiang Jia's downstairs and they went to school together. On the way, Jiang Jia told Sue that she knew there were two famous people in the school, one was Zhang Lu Jean and the other was Jean.