So far, the puzzle pieces leave little doubt that Mr. Kim is trying to forge a very different leadership style than his father, Kim Jong-il, whose countenance was dour enough to merit ribbing by the creators of South Park. The son, by comparison, appears to be more approachable (photos show him hooking arms with factory workers and soldiers); less threatened by foreign cultures and apparently more willing to admit failure (he told the nation of a botched rocket launch in April).

But there is also ample evidence that Mr. Kim, who took over late last year after his father’s death, does not plan to veer far from his father’s and grandfather’s governing policies on most issues, including maintaining a strong military and nuclear arms program and issuing frequent, florid threats against South Korea and the United States. Mr. Kim launched the rocket in April despite the likelihood that it would kill a new food aid agreement with the United States, which it did, and annoy the North’s last true ally, China, which had urged restraint.

It became clear early on that Mr. Kim aimed to style himself after his grandfather, Kim Il-sung, the more popular founder of the country, rather than his father. The youngest Mr. Kim claps his hands the same way his grandfather did and sports a similar hairdo with high-trimmed sideburns. In recent weeks, he hosted a huge children’s day celebration, ensuring he would be seen surrounded by happy and well-fed youngsters, just as his grandfather often was depicted in state propaganda.

But over time, Kim Jong-un has also begun to carve out his own leadership style, striving to come across as youthful and more pragmatic.

“He is much more willing to acknowledge challenges, problems and even failures,” said John Delury, a North Korea expert at Yonsei University in Seoul, who saw Mr. Kim’s strategy as aimed at “turning his potential weakness — youth and inexperience — into a political strength: dynamism and energy.”

He has delivered at least two public speeches, something his reclusive father never did. He was even shown visiting restaurants that sell pizza, hamburgers and French fries — Western foods that began appearing in Pyongyang several years ago but were not fully endorsed by his father.