The conventional wisdom is that a woman could never ascend to the leadership of North Korea, a country stuck in a time warp of passé fashions, hairdos, music, and social mores. A toxic mix of Confucianism and totalitarianism indentures women to their husbands, to their in-laws, and, ultimately, to a male-dominated regime. With a few exceptions (the best known being the vice foreign minister, Choe Son Hui), North Korea’s senior cadres are almost entirely male. The Supreme People’s Assembly—which currently has six hundred and eighty-seven members—is supposed to set aside twenty per cent of its seats for women, but the percentage has frequently dipped lower. And the primary function of these token deputies seems to be to brighten the optics, by wearing the jewel-toned, floor-length Korean gowns best known by the South Korean term hanbok. Since 1948, North Korea has been ruled by three men—the founder, his son, and his grandson—but, nevertheless, it is now conceivable that the fourth man will be a woman. That is because, with reports that Kim Jong Un is in failing health, the most obvious successor is his thirtysomething sister, Kim Yo Jong.

Kim Jong Un was a conspicuous no-show at ceremonies marking his grandfather’s birthday, on April 15th—the most important holiday on the North Korean calendar and an event that he has never missed since becoming leader, in 2011. A series of missile tests scheduled to coincide with the holiday went off without the customary footage of Kim watching from a viewing stand or peering through binoculars. North Korea’s official news agency, KCNA, continues to report on his purported activities (such as greetings and birthday messages sent to allies), but no reliable photographs of him have emerged since April 11th.

Last week, CNN reported that he was in “grave danger,” after having undergone surgery (an assertion echoed by a report from a Japanese magazine on Saturday that claimed he was brain-dead after a failed operation to insert a stent), while the Daily NK, a respected online newspaper based in Seoul, said that he was recovering after a cardiovascular procedure. “Something seems to be wrong,’’ the paper concluded, on Friday. Until “state media provides decisive evidence of his whereabouts and well-being, rumors will thus likely continue to emerge—and uncertainty will prevail.” So far, that hasn’t happened. The same day, Reuters reported that China had dispatched a team to North Korea that included medical personnel. Saturday was another holiday, marking the founding of North Korea’s armed services, and Kim Jong Un was missing from North Korea’s television coverage of the ceremonies, according to South Korea’s Yonhap News Service. Although much news about North Korea proves to be inaccurate—North Korean officials who vanish without explanation, and others who are thought to have been executed, frequently show up months later in meetings or parades—these reports make clear that North Korea needs to have a contingency plan for succession.

In the background of all this intrigue is the coronavirus crisis. Although North Korea implausibly claims to have no cases, the threat of contagion could be a reason that Kim has made no public appearances. Despite his youth—he is believed to be thirty-six—he is a heavy smoker and drinker who moves like a man decades older, with labored breathing and a limp. According to a biography published last year, Anna Fifield’s “The Great Successor,” medical experts who analyzed publicly available footage of the leader, who stands five feet seven inches, estimated his weight at one point to be three hundred pounds.

“If something happens, Kim Yo Jong is the logical successor,’’ Sue Mi Terry, a former North Korea analyst for the C.I.A., told me. “It is an open question whether North Korean élites would accept a woman, but they would have a more difficult time accepting somebody outside the Kim family.’’ Kim Yo Jong is the youngest known grandchild of Kim Il Sung, carrying what North Koreans revere as a pure bloodline that originated on Mount Paektu, a volcano on the border with China, which is the mythical birthplace of the Korean people. She was reportedly a favorite of her father, Kim Jong Il, who ruled from 1994 until his death, in 2011, and who, according to a former Russian official, Konstantin Pulikovsky, may have had a more enlightened attitude toward women than some of the North Korean élite. Pulikovsky, who travelled with Kim Jong Il by train and later wrote a memoir about the experience, told interviewers that the leader praised the intelligence of his daughter, while deriding his sons as “idle blockheads.”

If you look at the dynasty’s family tree, it appears that there are a number of Kims, males and females, but many have been exiled or purged, or worse; Kim’s oldest half brother, Kim Jong Nam, was assassinated in Malaysia, in 2017. Kim Jong Il had seven children with four women, but Yo Jong and Jong Un were born to the same mother, and spent at least part of their childhood together with another brother in Bern, Switzerland, where they attended elementary school under the guise of being the children of a North Korean diplomat.

Yo Jong didn’t attract much attention until Kim Jong Il’s funeral procession, in Pyongyang, on December 28, 2011. A pale, slim, almost waif-like figure, she was so little known that analysts at first speculated that she might be Kim Jong Un’s wife. She subsequently started popping up in official videos, moving gradually from the background to center stage. She made a well-publicized international début when she attended the opening of the 2018 Olympics, in Pyeongchang, South Korea, upstaging the dour U.S. representative, Vice-President Mike Pence, and earning the title in the South Korean media of “North Korean Ivanka Trump.” (“They marveled at her barely-there makeup and her lack of bling. They commented on her plain black outfits and simple purse. They noted the flower-shaped clip that kept her hair back in a no-nonsense style’’ is how the Washington Post reviewed her reception.)

Unlike Kim Jong Un’s wife, the glamorous Ri Sol Ju, Yo Jong appears in public wearing ladylike heels and dark suits, with an occasional pussy-bow blouse. She has often been seen in meetings carrying gifts, taking notes, or fetching pens for her brother. At the Hanoi summit with President Trump last year, she held an ashtray to collect his cigarette butts—a subservient but crucial task, since the North Koreans are compulsive about not leaving behind any trace of leadership DNA. Nonetheless, the official titles conferred on Yo Jong leave little doubt that she is on the ascent. In 2014, she was identified as the deputy director of the ruling Workers Party’s department of propaganda and agitation. In 2017, she was made an alternate member of the Politburo, reportedly only the second woman ever to hold that position. (The first was Kim Kyong Hui, Kim Jong Il’s sister.) More tellingly, the official KCNA news service ran a March 22nd statement attributed to her, thanking Donald Trump for a letter in which he offered coöperation in fighting the coronavirus. In the statement, she praised Trump for sending the letter at a time when “big difficulties and challenges lie ahead in the way of developing ties” between the countries.