With North Korea saying nothing so far about outside media reports that leader Kim Jong Un may be unwell, there's renewed worry about who's next in line to run a nuclear-armed country that's been ruled by the same family for seven decades.
The family's mythical "Paektu" bloodline, named after the highest peak on the Korean Peninsula, is said to give only direct family members the right to rule the nation.
That makes Kim's younger sister, senior ruling party official Kim Yo Jong, the most likely candidate to step in if her brother is gravely ill, incapacitated or dies.
Who is Kim Yo Jong? The potential successor of Kim Jong Un
Kim Yo Jong is the youngest child and the only daughter of Kim Jong II. According to the US Treasury Department, she was born in Pyongyang on September 26, 1989 but South Korea's intelligence service says that she was born in 1987.
She attended school in Bern, Switzerland just like her older brothers. She went to Liebefeld-Steinhölzli public school for several years and lived in an apartment nearby. Interstingly, she went by the alias Pak Mi Hyang and has also taken ballet classes while she was in Bern. Her brothers Kim Jong Chol went by the name Pak Chol and Kim Jong Un by Pak Un while they studied in Bern.
Well, she is believed to have returned to North Korea in 2000 or 2001 and completed her special classes at Kim II Sung University in Pyongyang. Her father later told his interlocutors that Kim Yo Jong was interested in politics.
While she was not seen in public for a decade after she returned to North Korea, she is believed to have made her debut in the media during her fathers funeral in 2011.
During all these years, she is believed to have been groomed for a leadership role and politics by her aunt Kim Kyong Hui.
Now, Kim Yo Jong is in charge of North Korea's propaganda affairs, and earlier this month was made an alternate member of the powerful Politburo.
She has frequently appeared with her brother at public activities, standing out among elderly male officials. She accompanied Kim Jong Un on his high-stakes summits with U.S. President Donald Trump and other world leaders in recent years. Her proximity to him during those summits led many outsiders to believe she's essentially North Korea's No. 2 official.
Well, the fact that North Korea is an extremely patriarchal society has led some to wonder if Kim Yo Jong would only serve as a temporary figurehead and then be replaced by a collective leadership similar to ones established after the deaths of other Communist dictators.
