HANOI (Reuters) - Ready with an ashtray at a railway station, taking away gifts of flowers and giving directions to staff, Kim Yo Jong has been rushed off her feet as personal secretary to her brother and North Korean leader Kim Jong Un in Vietnam.

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Kim Yo Jong, who holds the title of vice director of the ruling Workers’ Party, came to the world’s attention at the Winter Olympics in South Korea a year ago, when her big smile and relaxed manner made her a hit with many south of the DMZ.

But it has been non-stop for her on the trip to Hanoi, trailing her brother during his second summit with U.S. President Donald Trump, her hair neatly half swept back in trademark fashion, making sure everything goes like clockwork.

Kim Yo Jong, 29, in high heels and black two-piece suit, was ubiquitous even before her brother, a stickler for cleanliness, arrived in Hanoi on Tuesday.

As Kim Jong Un took a cigarette break at a railway station in the southern Chinese city of Nanning, she approached him holding a crystal ashtray in two hands, footage from Japanese broadcaster TBS showed.

After Kim’s train rolled into the Vietnamese border station of Dong Dang, Kim Yo Jong was the first person to emerge, alongside protocol chief Kim Chang Son.

She appeared at one point to slightly push aside Kim Yong Chol, the leader’s chief nuclear envoy and top aide, as she sprinted from the train towards her brother and took welcome flowers from him.

When Kim Jong Un signed an agreement with Trump after their first summit in Singapore last June, he ditched a pen sterilized by his security officials in favor of one offered by his sister.

“It is most fascinating because we see her discharging technical and hygienic tasks on one hand, but she also has to fulfill certain ceremonial tasks as one of the visiting VIPs,” said Michael Madden, a North Korea leadership expert at the Washington-based Stimson Centre’s 38 North think tank.

The Kims’ keenness on cleanliness is rooted in the era of their late father, Kim Jong Il, when immaculateness was key and sanitizers were widely used, Madden said.

Experts also say the use of a personal ashtray or pen in particular is intended to prevent the ruling family’s DNA being collected by foreign governments.

“The paranoia about medical intelligence involved Kim Jong Il, so the security units may have continued the policy with his son,” Madden said.

Since her debut on state media in December 2011, Kim Yo Jong has quickly climbed the leadership ladder. She was named as an alternate member of the party’s all-powerful politburo in late 2017 as her brother draws his most important people closer to the center of power.

At the Olympics, her every move was scrutinized. Crowds applauded as she stood for the South Korean anthem during the opening ceremony.

But some critics said the aloofness and high-tilted chin spoke of someone who sees herself “above anyone else”.

As for the summit, Trump said he and Kim Jong Un had failed to reach agreement on denuclearization due to North Korean demands to lift punishing U.S.-led sanctions.