Kim Jong Un's arrival in China for his first ever multilateral meeting was always going to make headlines.

But it was the smartly-dressed girl standing just behind him as he exited his armoured train which caught Korea watchers' attention: Kim Ju Ae, the North Korean leader's daughter.

According to South Korea's spy agency, Miss Kim is her father's most likely successor.

But details - including her exact age - are thin on the ground. So what exactly do we know?

Miss Kim has, for a number of years, been believed to be the second of Kim Jong Un's and his wife, Ri Sol-Ju's, three children. The exact number, and their order, is by no means certain however: Kim is very secretive about his family, only introducing his wife to the public after they had been married for some time.

Kim Ju Ae is their only child whose existence has been confirmed by the country's leadership. No other child has been seen in public.

News of her existence first emerged through an unlikely source: the basketball player Dennis Rodman, who revealed to The Guardian newspaper back in 2013 that he "held their baby Ju Ae" during a trip to the secretive state.

Little was then heard about her until November 2022, when she appeared alongside her father at the launch of an intercontinental ballistic missile (ICBM).

By February the next year, she was appearing on postage stamps and attending banquets for top officials - described as Kim Jong Un's "respected" daughter.

The adjective "respected" is reserved for North Korea's most revered. In her father's case, he was referred to as "respected comrade" only after his status as future leader was cemented.

South Korea's National Intelligence Service (NIS) provided lawmakers with a few extra details on the little girl at around the same time, according to news agency AP.

They said she enjoyed horse riding, skiing and swimming, and was home-schooled in the capital Pyongyang. They suggested she was around 10 years old.

By January 2024, the NIS had come to another conclusion: that the little girl was the "most likely" successor to Kim Jong Un - although they noted there were "many variables" still in play, not least because of her father's young age.

Since then, she has appeared by her father's side on numerous occasions. Standing next to him at ICBM launches and military parades, she has taken centre stage and received military salutes from senior military commanders.

But Tuesday marked the first time she has been seen outside North Korea, and the trip is likely to further fuel speculation she may succeed her father.

The Kim family, who have ruled North Korea since 1948, tell citizens they hail from a sacred bloodline, meaning only they can lead the country.

However, there is speculation that Kim has introduced his daughter at this point to try to overcome prejudice in the deeply patriarchal state, which has never been led by a woman.