Japan's relations with Southeast Asia have come a long way in nine years. Prime Minister Yasuhiro Nakasone - just returned from a tour of five Southeast Asian nations - is pleased that the foundations of the region's relations with Japan are on firm ground.
His trip contrasts with a similar tour by Prime Minister Kakuei Tanaka in 1974, which was accompanied by anti-Japanese riots in Jakarta and Bangkok.
Tokyo officials say Mr. Nakasone's achievements on his tour were the allaying of suspicions about Japan's current military buildup and securing the outright blessing of the five leaders he met.
Nakasone apparently succeeded in building a personal friendship with the five leaders of the Association of Southeast Asian Nations (ASEAN). Singapore Prime Minister Lee Kuan Yew, for example, complimented him on being so different from his predecessors who used ''soft and misty language.''
Of particular concern were the Philippines and Indonesia. Philippines President Ferdinand Marcos went to the heart of one important issue. Referring to an American-backed idea for the Japanese to defend vital sea lanes out to 1, 000 miles from their shores, Marcos pulled out a map of the region and asked, ''Where is your limit. . . . Has it reached the Philippines?''
''No,'' Nakasone replied with a laugh. And that, reported officials at the meeting, was that. Marcos later told reporters: ''I am convinced he [Nakasone] has no intention of building up a strong military [for] Japan with capability for attack.''
Indonesia, which also has memories of wartime Japanese occupation, was also apprehensive about Nakasone's hawkish image on defense issues. On a visit to Washington earlier this year, President Suharto expressed his concern that the US was pushing Japan too hard to become a military power. But after meeting Nakasone in Jakarta, the Indonesian leader said he had no objections to Japan's current plans ''if it is purely in self-defense.''
That simple nod took a lot of preparation by the Japanese. Indonesian military leaders were invited to Tokyo for background briefings on the purely defensive nature of the military buildup, and Nakasone gave interviews to ASEAN journalists to set the stage for his tour.
Singapore Prime Minister Lee and Malaysian Prime Minister Datuk Seri Mahathir Mohamad were already supporters, having recently visited Tokyo. And Thailand also gave strong backing.
Thus, as the defense issue was the main source of apprehension among Japanese officials prior to the Nakasone tour, it is being hailed as a success. It is ironic, however, that the man who seems to have allayed ASEAN suspicions should be the one who has been labeled as Japan's most hawkish prime minister for many years.
Nakasone carried with him economic assistance offers and yen credits in substantial amounts. However, he generally opted to build on the economic programs of his predecessors rather than open major new initiatives. Winding up the tour in Malaysia, Nakasone summed up his ideas in what aides are calling the ''Kuala Lumpur declaration.'' In brief, he promised:
* ASEAN will continue to enjoy top priority as a recipient of Japanese economic aid.
* Japan will step up technological aid, including a proposed ''plant renovation cooperation'' program aimed at updating obsolete facilities originally built with Japanese economic assistance. There will also be regular ministerial conferences on scientific and technical cooperation.
* Japan will expand its quotas on as many as possible of the import items of key interest to ASEAN in order to achieve more balanced trade.
* A personnel exchange program will be launched under which 750 ASEAN youths will be invited to Japan annually for a month-long study trip.
Throughout his tour, Nakasone spoke of his dream of ''Asia as one community.'' But he faced an old question: ''How is Japan going to give meat to its words,'' as one Malaysian newspaper put it.
Buoyed with the success of his trip, Nakasone has promised to speak on behalf of the ASEAN countries at the forthcoming seven industrialized nations summit in Williamsburg, Va.
But Mainichi correspondent Toichi Suzuki reported conversations with a number of ASEAN colleagues in which it was said: ''Why should Japan presume to speak on behalf of us? She has done nothing to deserve being treated as a leader.
''Anyway, our own politicians have good contacts with the United States and Europe and don't need to go through a third party.''