Getting ready for the rare gathering -- the first of its kind for nearly 40 years -- has involved mobilising the entire country in a 70-day campaign that only ended on Monday.
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The congress opens on Friday and is expected to cement Kim's status as supreme leader more than four years after he came to power following the death of his father Kim Jong-Il.
The ruling party's official mouthpiece, the Rodong Sinmun daily, said the coming congress was a "sacred" event that would enshrine Kim's achievements, from infrastructure projects to developing submarine-launched ballistic missiles.
These were victories won, the newspaper said, through a national struggle against UN sanctions over the North's nuclear programme, the threat posed by US-South Korea military drills and international criticism of the North's human rights record.
Referring to the country's nuclear arsenal as a "precious sword", Rodong said the weapons were a "treasure of all happiness that will ensure many things in decades to come".
There has been widespread speculation -- backed in part by satellite imagery -- that North Korea is preparing to carry out a fifth nuclear test just before, or even during, the congress to underline its claim to be a genuine nuclear power.
"Regarding the preparatory situation, the North is able to carry out a test any time it wants," the South Korean Unification Ministry said Wednesday.
The North conducted its fourth nuclear test in January, followed by a long-range rocket launch and a flurry of other missile and weapons tests.
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Not all of them were successful, with the failure in recent weeks of three separate efforts to test fire a powerful, new mid-range ballistic missile capable of striking US bases on the Pacific island of Guam.
Pyongyang has invited the world's media to cover the congress, while offering few clues as to what might -- or might not -- be announced at the event.
And it has still not officially confirmed just how long the gathering will go on for.
The last congress lasted four days and was held in 1980, when Kim's grandfather, founding leader Kim Il-Sung was still in power.
Defector-run news websites in Seoul, with sources in the North, have reported a tightening of security around Pyongyang in recent weeks, with strict controls on movement in and out of the capital.
"Anyone getting in trouble with the authorities during the congress preparation period is being treated as a political offender and punished accordingly," the Daily NK website quoted one source as saying.
State media, meanwhile, have been busy during the 70-day campaign running endless stories extolling examples of individual selflessness and sacrifice.
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One farming couple volunteered to keep working on their wedding day, the Rodong Sinmun proclaimed, while a woman security guard insisted on turning up for duty the day after her husband died.
Some observers believe Kim Jong-Un will use the congress to confirm the completion of North Korea's nuclear deterrent and announce a switch in focus towards economic development.
In his very first public address as leader, at a military parade in April 2012, Kim had said he was determined that North Koreans would "never have to tighten their belts again".
The need to raise living standards has been a constant refrain of his annual New Year addresses, although analysts note that they have been largely devoid of any specific policy initiatives.
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