The public displays of amity at the recent meeting of Japanese and South Korean lawmakers here only partially masked the remaining tensions and problems between the two countries.

By tacit agreement, potentially difficult topics were shelved or conspicuously ignored, for neither Japanese Foreign Minister Iichiro Hotoyama nor his South Korean counterpart, Park Tong Jin, was eager to fuel a public debate.

Problems left to one side include alleged influence buying in Japan by South Korea's Central Intelligence Agency, dubious business dealings by companies of both countries, both countries' claims to the same island and a renewed controversy over the 1973 Tokyo kidnapping of Kim Dae Jung, a leading South Korean politician.

The major discussion among the ministers and the group of 120 parliamentarians from both nations centered on the Carter administration's proposal to withdraw U.S. ground forces from South Korea. Even on this subject, there was a divergence of views and national interest.

The South Koreans want the pullout delayed several years until their defense forces are strengthended. The Japanese have backed off from their initial resistance to Carter's plan and now declare it an issue between the United States and South Korea. The Koreans had to be content with a mildly worded expression of "serious concern" in the parliamentarians' joint letter to Carter.

Geography, the post-World War II division of Korea, and the Korean War threw Japan and South Korea into political and economic partnership despite their long history of war and enmity.

Their mutual dependance is based on opposition to the communism that surrounds them and on their separate security treaties with the United States. In thelast 12 years, since Seoul and Tokyo normalized relations, Japan has played a key role in Korea's industrialization by supplying technology, $1,365 million in public and commercial loans and $587 millions in direct investment. With that investment protected by the U.S. military commitment to Seoul, Japan has developed South Korea as an acillary industrial base and as a market for its exports second only to the United States. The two-way trade last year totaled $3.8 billion with a $900 million surplus favoring Japan.

Still, there are those who say the foundations are too flimsy for so heavy a structure. On both sides there is the emotional residue from Japan's 1905-45 occupation of the Korean peninsula. The Japanese are widely disliked, even hated, in Korea, and many Japanese regard the Koreans as a lesser race. Though both governments are convinced that close links are in their national interest, opposition groups in both nations raise serious cultural, ideological and economic objections.

Park's much-harassed domestic critics assert that he has pandered to Japanese tourists by encouraging prostitution and has sold the country out to "economic imperialism."

The question of what Japan's policy should be toward the two Koreas remains the country's most divisive issue. The roughly 600,000 Koreans in Japan are split into equal, mutually antagonistic groups loyal to South or North Korea. With U.S. encouragement, Japan's successive conservative governments have favored South Korea and maintained minimal ties with the Communist north.Most opposition members of parliament are critical of the authoritarian south and wish to open diplomatic relations with Pyong-yang.

Japan is the friendly gate to the outside world for the isolated and paranoid South Koreans, who are alarmed at the notion that a pro-Pyong-yang government could come to power in Tokyo.

Such fears might have prompted Seoul to make secret political contributions to favorably disposed members of Japan's ruling Liberal-Democratic Party.

The old rumors of an intricate bribe and kickback structure gained a new momentum when Donald L. Ranard, former U.S. State Department Korean affairs specialist and a former Korean diplomat, Lee Jae Hyon, recently alleged that payoffs had been made.

Officials of both countries have denied the charges, but under mounting pressure Japanese Premier Takeo Fukude has ordered an investigation. Another probe is to reexamine allegations that large bribes were paid in the sale of $40 million worth of subway cars to Seoul five years ago.

Especially sensitive is the newly reopened investigation into the abduction of former presidential candidate. Kim Dae Jung from a Tokyo hotel room in 1973. He was released in Seoul days later and the discovery of a South Korean diplomat's finger prints in the hotel room clinched, a general belief that it was a Korean Central Intelligence Agency operation. The Korean government denied responsibility, but apoligized and removed the diplomat. There is widespread sympathy here for Kim, who is now serving a five-year prison term for political offenses.

Ranard has since claimed that the Japanese government knew of KCIA responsibility for the kidnapping. The implication is that it ignored evidence of wrongdoing by the South Korean government to get a vital relationship back on track.