Japanese Prime Minister Yoshihiko Noda has opened a five-day visit to South Korea set to include a bilateral summit aimed at easing long-strained relations between the two Asian neighbors.

Mr. Noda arrived Tuesday in Seoul, where he was set to return Korean royal documents looted during Japan's occupation of the Korean Peninsula from 1910 to 1945. The return, promised last year by Mr. Noda's predecessor, Naoto Kahn, is widely seen as a goodwill gesture aimed at improving ties strained most recently by ownership disputes over islets in the northern Pacific region.

The Japanese prime minister and South Korean President Lee Myung-Bak were set to discuss a proposed free trade pact, a series of exchange programs and efforts to persuade North Korea to abandon its rogue nuclear program.

Earlier this year, South Korean air carrier Korean Air made a test flight over one of the outcroppings at the center of the territorial disputes. Tokyo responded by banning its public workers from the airlines for a month — a move that prompted South Korea to bar three Japanese lawmakers from landing in Seoul.

The two countries also remain locked in a diplomatic standoff over South Korean demands that Japan compensate colonial-era Korean women forced into sexual slavery during the Japanese occupation. Tokyo has rejected those demands, saying the issue was settled in a 1965 treaty that normalized bilateral ties.

Despite their historical antipathy, the two governments work closely with The United States, China and Russia in six-party negotiations aimed at ending North Korea's nuclear weapons development.