As some North Korea watchers parse the statements and style of new leader Kim Jong Eun for clues to his personality, other sleuths are plumbing the mystery of Mr. Kim's ancestry.

But women who went back to North Korea from Japan often changed Jya -- a common ending for girl's names in Japan pronounced "ko" in Japanese -- to something else, to keep from sounding too Japanese, Mr. Koh told JRT. Mr. Koh said he felt sure he'd found Kim Jong Eun's family.

"This...