The influential sister of North Korean leader Kim Jong-un is to attend Friday’s opening ceremony of the Winter Olympic Games, which are being held in the South, ministers in Seoul say.
Kim Yo-jong is the youngest daughter of late leader Kim Jong-il and her role was strengthened last year when she was promoted to the politburo.
Both Koreas will march under one flag at the opening ceremony.
The North’s participation has been seen as a thawing of bilateral ties.
However, experts say it is unlikely to have any impact on the North’s nuclear ambitions.
The US believes the North is using the Olympics for propaganda purposes and is sending Vice-President Mike Pence to the opening ceremony to counter it.
“We’re travelling to the Olympics to make sure that North Korea doesn’t use the powerful symbolism in the backdrop of the Winter Olympics to paper over the truth about their regime,” he said.
Kim Yo-jong, who shares the same mother as Kim Jong-un, will accompany the North’s ceremonial head of state.
Most of the 280-member North Korean delegation, including a team of cheerleaders, arrived in the South on Wednesday.
The delegation, led by North Korean Sports Minister Kim Il-guk, includes 229 cheerleaders, four officials from the National Olympic Committee, 26 taekwondo demonstrators and 21 journalists.
The team arrived via a western border at 09:28 local time (00:26 GMT), the Yonhap news agency reported.
Only 10 athletes will compete for the North at the Games, along with another 12 as part of a unified Korean women’s ice hockey team.
Believed born in 1987, Kim Yo-jong is said to be very close to Kim Jong-un, who is about four years older than her. The two of them lived and studied in Berne, Switzerland, at the same time.
She is reportedly married to the son of Choe Ryong-hae, the powerful party secretary, and is a senior official in the ruling Workers’ Party.
She has been in the spotlight sporadically in recent years, with her main job being to protect her brother’s image via her role in the party’s propaganda department.
She remains blacklisted by the US over alleged links to human rights abuses in North Korea.