Now I Get It: Who is Kim Jong Un's mysterious sister?

The sister of North Korean leader Kim Jong Un will make her debut on the world stage when she makes a landmark visit to South Korea for the Opening Ceremony of the 2018 Winter Olympics in PyeongChang. Kim Yo Jong will be the first immediate family member of the Kim dynasty to cross the border to the South since the Korean War ended in 1953. While she has primarily remained out of the spotlight, here is what is known or believed about her.