In his book "My Father, Kim Jong Il, and Me," which went on sale this week, Tokyo-based journalist Yoji Gomi describes the oldest son, Kim Jong Nam, as an intelligent gentleman who understands his country's problems.
Gomi says he met Kim Jong Nam by chance in Beijing in 2004. The brief encounter gave him just enough time to ask him who he was and hand him his business card. That led to over 150 emails spanning nearly eight years, and two interviews last year totaling seven hours, he told The Associated Press on Friday.
The book is a rare view into the family that has led the secretive country for decades. Since Kim Jong Il's death on Dec. 17, North Korea has been led by his youngest son, Kim Jong Un.
The book cites Kim Jong Nam's concerns over his brother's inexperience. In an email dated Jan. 3, Gomi's last contact from him, Kim Jong Nam wrote that "Jong Un will just be a figurehead, and the existing group of people who wield power are likely to take over my father's work," Gomi writes.
Kim Jong Nam believes that rigid North Korea must make Chinese-style economic reforms, and as a result fell from favor with his father, said Gomi, a Tokyo Shimbun newspaper journalist who had assignments in Seoul and Beijing.
"He dropped out of the succession race because he angered his father by calling for economic reforms and an open-door policy," Gomi said.
"Without reforms and liberalization, the collapse of the economy is within sight," he quoted Kim as saying in the book. "But reforms and opening up could also invite dangers for the regime."
Kim Jong Il is known to have three sons -- one from his second wife and two from his third.
Kim Jong Nam was seen as a possible successor until 2001, when he embarrassed the government by being caught trying to enter Japan with a fake passport. He said he wanted to visit Tokyo Disneyland.
He now spends much of his time in mainland China or in Macau -- the center of Asian gambling.
Gomi says his image in the media as a frivolous spendthrift is not what he really is.
"He had a very courteous demeanor, he was intelligent and very gracious in the way he spoke," Gomi said. "After having deeper conversations with him, I felt his analysis was insightful and he understands North Korea's weaknesses."
Soon after Kim Jong Il's funeral, Kim Jong Nam suggested in an interview with a Japanese TV network that he opposed the hereditary transfer of power to his young half brother -- a rare public sign of discord in the tightly choreographed succession process.
Gomi said Kim Jong Nam doesn't seem eager to become leader but is envious of his half brother's ascension.
"I get the impression that he thinks 'I used to be in that position, but now someone who's much younger than I, in his 20s, is in that seat. That isn't right. I can do a better job,"' he said.
Gomi said he thinks Kim Jong Nam is likely to continue living abroad, mostly in China.
"I would have liked to see him take the leadership. It's fun to imagine at least," he said. "If he were leader, I think North Korea would become much closer to Japan and South Korea. But because he is easy going, the country might collapse anyway."