In May, a newly formed group led by Okinawan university professors held a symposium on independence that drew 250 people. A tiny political party that advocates separation from Japan through peaceful means has been revived after decades of dormancy, though its candidates have fared poorly in recent elections. And on his blog, a member of Parliament from Okinawa recently went so far as to post an entry titled “Okinawa, It’s Finally Time for Independence From Yamato,” using the Okinawan word for the rest of Japan.

“Before, independence was just something we philosophized about over drinks,” said Masahide Ota, a former governor of Okinawa, who is not a member of the movement.

“Now, it is being taken much more seriously.”

The independence movement remains nascent, with a few hundred active adherents at most. But Mr. Ota and others say it still has the potential to complicate Japan’s unfolding contest with China for influence in the region.

That struggle expanded recently to include what appears to be a semiofficial campaign in China to question Japanese rule of Okinawa. Some analysts see the campaign as a ploy to strengthen China’s hand in a dispute over a smaller group of islands that has captured international headlines in recent months. Some Chinese scholars have called for exploiting the independence movement to say there are splits even in Japan over the legitimate ownership of islands annexed during Japan’s imperial expansion in the late 19th century, as Okinawa and the smaller island group were.

Okinawa has long looked and felt different from the rest of Japan, with the islands’ tropical climate, vibrant musical culture and lower average incomes setting it apart. Strategically situated in the center of East Asia, the islands, once known as the Kingdom of the Ryukyus, have had a tortured history with Japan since the takeover, including the forced suicides of Okinawan civilians by Japanese troops during World War II and the imposition of American bases after the war.