Tokyo — Not since immediate after World War II has a Japanese prime minister assumed office facing a wider range of seemingly intractable problems.
Yasuhiro Nakasone has inherited a host of difficulties that have been building up inexorably over the past decade, resulting in the downfall of five prime ministers since 1972 after an average of two years in power.Should he fail , too, ''Nakasone will be forced to exit after a much shorter term than his predecessor,'' predicted political commentator Toshiya Kawahara.
Mr. Nakasone begins his administration with the same political weaknesses and factional disunity that hobbled and eventually toppled the five previous administrations. His relations with other powerful figures within the party are shaky after the long, divisive power struggle that led to his election, and considerable distrust and unease remains.
A major built-in weakness of the new administration is its heavy dependence on the goodwill and support of former Prime Minister Kakuei Tanaka. Officially, Tanaka left the ruling Liberal Democratic Party (LDP) in 1976 after he was arrested in the Lockheed bribes scandal. But his influence is as strong as ever, working through the 108 Dietmen who form the LDP's largest faction.
Given his narrow power base Nakasone could not have become prime minister without the support of the Tanaka faction. This fact of political life is reflected in Tanaka supporters gaining six Cabinet posts as well as the powerful position of LDP secretary-general.
This provoked immediate outrage within the party, with one LDP member complaining, ''Tanaka has hijacked the government.'' Newspapers are referring to it derisively as the ''Tanaka Cabinet,'' with Nakasone merely a figurehead.
A close Tanaka confidant, former Police Superintendent General Akira Hatano, has been given the Justice Ministry. This is a highly sensitive portfolio because the Tokyo District Court is to hand down its verdict on the former prime minister next year. (It is widely assumed he will be found guilty.)
Mr. Nakasone's pressing political task is to rebuild the ruling party, which has grown lax and antiquated through more than three decades of uninterrupted rule, breeding public apathy and alienating many Japanese from the political process.
Democracy has had a hard time taking root in Japan, mainly due to a lack of viable alternatives to the LDP. The opposition parties, complained a respected political analyst, have come to see themselves as just that - opposed to the policies of the LDP, but not presenting any concrete programs that would persuade voters to put the opposition in charge.
Ichiko Kawakami, a housewife, sums up the postwar generation's feelings: ''My father is a doctor. He doesn't like the LDP at all, but he votes for it because he is frightened that if the opposition parties gain power his income will . . . suffer.
''I think a lot of older Japanese feel that way, voting out of fear for their continued livelihood rather than political conviction. By comparison, most of the younger people I know never bother to vote because they feel the LDP is hopelessly corrupt but there is no one else worth voting for.''
The Nakasone government could well be a transitional one. Seizaburo Sato, professor of political science at Tokyo Univerity, notes that in recent years the majority of opposition parties have shifted ground so that there are no major differences in basic principles between them and the LDP.
Already at a local level there are LDP-opposition coalitions, ''which means there is the possibility the LDP will split. Some factions of the LDP can now establish a new ruling party if they collaborate with some opposition parties. . . . It is now possible that the political stability which has been characteristic of postwar Japan will end.''
In addition to shoring up the structure of the ruling party, Mr. Nakasone has other equally pressing issues on his agenda. Top priority is fiscal reform, critical to economic recovery. The habit of increasing the annual budget became so ingrained in the prosperous postwar years that governments in the more austere 1970s were unable to change course.
Nakasone has pledged to continue Zenko Suzuki's drive for austere government.
Diplomatically, the major need is to mend fences with the United States, especially in such areas as defense spending and trade friction.
Nakasone is committed to greater spending so Japan can defend itself. He strongly supports the US-Japan security treaty, saying the US ''is the spear and Japan the shield. While the responsibility for attack lies with the United States, defense is Japan's duty.''
At the same time, he has to accept the restraints imposed by Japan's current fiscal problems and a public consensus that opposes increases in defense spending while social welfare, public works, and other government spending are being cut to the bone. Instead of seeking an immediate increase, the new prime minister will have to battle just to keep what was originally allocated for next year.
On top of this is the growing sentiment toward trade protectionism which, if acted upon, will likely inflict further damage on a Japanese economy that is losing its dynamism in many key sectors. Demands continue to mount from the US and Western Europe for the Japanese market to be rapidly opened to their agricultural and industrial products.
For the US, the main issue at present is free access for such important agricultural products as beef, citrus fruits, and tobacco, all now subject to tight Japanese quotas.
Nakasone finds himself boxed in. He needs good relations with the US, but an upper house election is scheduled for next year, possibly together with an early lower house vote.
Some 60 percent of LDP Dietmen rely on the farm vote for their survival. They will certainly oppose any steps that threaten the current heavily subsidized, cushioned existence of the grossly inefficient farming sector.
Nakasone has said he will go to Washington as early as this January to coordinate Japanese-American thinking on defense and other issues.