THE RIGHT-HAND MAN
Mr Kim Yong Chol, a senior party official and the counterpart to US Secretary of State Mike Pompeo, has been on the front lines of the ongoing diplomacy between Pyongyang and Washington.
He is seen as Mr Kim Jong Un's most trusted aide and is accompanying him on his olive-green train en route to Vietnam.
Mr Kim Yong Chol flew to Washington with a letter for President Donald Trump from the North Korean leader last month, after which the White House announced the second summit to break months of deadlock since the first meeting in Singapore last June.
He was in charge of overseeing negotiations in Singapore - the first-ever summit between the leaders of the United States and North Korea - and likely remains a key player in Hanoi.
Ms Kim Yo Jong has been at her brother's side since his debut on the international stage in a visit to Beijing last year, and is once again travelling with him, this time to Hanoi.
She has been on hand at all times - taking her brother's coat, studiously writing down his remarks and handing him a pen for signing joint statements with leaders of China, South Korea and the US.
She grabbed headlines at the Pyeongchang Winter Olympics last year as the public face of the North Korean delegation sent to the Games.
But she has also earned a reputation of unknowingly putting herself before the camera, straying into the shots of her brother and heads of state on several occasions before scurrying out of the picture.
Mr Kim Hyok Chol arrived in Hanoi one week ahead of the summit for preparatory talks with US special envoy Stephen Biegun.
A former North Korean ambassador to Spain - before he was expelled amid soaring nuclear tensions in 2017 - Mr Kim Hyok Chol was introduced as Mr Biegun's counterpart last month when he visited the White House with Mr Kim Yong Chol.
Mr Kim Hyok Chol and Mr Biegun have engaged in marathon negotiations and are expected to wrangle over the agenda of the summit - likely to include the terms of denuclearisation - until the actual day of the meeting.
Mr Kim Chang Son is the de facto chief of staff to the North Korean leader, overseeing the security and protocol of key events attended by Mr Kim Jong Un.
Both the North Korean leader and his sister are reportedly very fond of Mr Kim Chang Son, who served as the "trusted butler" to the Kim family under Mr Kim Jong Il - the late father and predecessor to Mr Kim Jong Un.
Mr Kim Chang Son arrived in Hanoi nearly two weeks ahead of the Feb 27-28 meeting, closely touring and inspecting prospective sites for the summit and the accommodation of the North Korean leadership.
Around 100 North Korean bodyguards flew in from Pyongyang on Sunday as their leader was passing through China towards Hanoi, according to Vietnamese media.
The army of security officials remained at arm's length from Mr Kim Jong Un at his landmark meeting with Mr Donald Trump - from the summit venues to when he roamed the streets of Singapore in a surprise night out on the eve of the meeting.
The men - dressed in matching sharp, black suits - earned the nickname "human shield" at Mr Kim's first summit with South Korean President Moon Jae-in, when a dozen of them trotted alongside his Mercedes-Benz.