Is Kim Jong-un the grandson of a traitor?
Julian Ryall in Tokyo
A Japanese researcher says he has discovered that North Korean leader Kim Jong-un's maternal grandfather worked for the Imperial Japanese Army during the second world war, making uniforms for soldiers whose comrades were hunting Kim's other grandfather, Kim Il-sung.
Such a lineage would technically make Kim Jong-un part of North Korea's 'hostile class' and the grandson of a traitor. That could have 'a devastating impact on North Korean society', says researcher Ken Kato.
Kato, a Japanese human rights activist who discovered documentation of Kim's ancestor files in military archives in Tokyo and the library of the Japanese parliament, said his evidence that Kim's maternal grandfather - Ko Gyon-tek - was a collaborator undermines his legitimacy.
'Now that it is clear Kim Jong-un is actually from the pariah class, according to North Korea's political classification system, the entire foundations of the system have been proved to be nonsense,' Kato said.
'He has to liberate all the others who have been identified as 'hostile class' and halt human rights abuses immediately.'
Kato unearthed Imperial Japanese Army documents that show that during the war, Ko worked at the Hirota sewing factory in Osaka making uniforms for Japanese soldiers, at a time when imperial troops were hunting Kim Il-sung, the guerilla leader who would much later become his daughter's father-in-law.
To have collaborated with the Japanese occupiers of Korea would normally have meant a long incarceration in North Korea's notorious gulags, for the traitor and his entire family. Ko probably avoided that fate after he returned to North Korea in the early 1960s thanks to his daughter being in the favour of Kim Jong-il.
Born on Jeju Island in what is now South Korea, Ko moved to Japan in 1929 and was involved in a number of businesses, both legal and illegal. During the war years, the clothing factory where he worked was controlled by the Ministry of War.
Kim Jong-un's mother, Ko Young-hee, was born in Osaka in June 1953, but the family was forced to move to North Korea in May 1961 after her father was arrested by Japanese police on charges of human trafficking and deported.
Ko apparently managed to conceal his past and found work in a North Korean chemical factory, the records indicate, while his daughter began to dance with the Mansudae Art Troupe. It was as a dancer that she caught the eye of Kim Jong-il, who was already being groomed to take over North Korea from Kim Il-sung.
Their first child, Kim Jong-chul, was born in 1981 and Kim Jong-un followed in January 1983. Ko Young-hee died in Paris in August 2004, apparently of breast cancer. Ko Gyon-tek is believed to have died in 1999.
Kim Jong-il, who died last December, had a series of marriages and mistresses and Kim Jong-un is understood to be his fourth child.
'There is a strict classification system that is based on pedigree in Korea that dates back to the 6th century and is part of the culture,' said Kato. 'I am sure that Kim Jong-un does not know that his grandfather worked in a Japanese military factory because even the fact that his mother was a returnee from Japan was considered a top secret in the North.
'Not only was he a returnee, but he was a collaborator,' Kato said. 'That made him the lowest of the low in North Korean society and ordinarily he and his family would have gone into the prison camp system.
'Under their rules, his family should have gone to concentration camps.'