The election of Masayoshi Ohira as prime minister will continue the line of moderately conservative governments Japan as adhered to since the Liberal Democratic Party claimed its first majority more than two decades ago.

Ohira may be a trifle less devoted to rapid economic growth than some of his predecessors, and he is a bit less enthusiastic about generating a debate over military defense than was Prime Minister Takeo Feukuda. He also will be somewhat more accommodating to opposition parties than Fukuda, who was inclined to truculence, but there will be no sharp change in directions under Ohira's tenure.

These are the views of observers here who base their judgement on association with Ohira or on a reading of his record in nearly 32 years of politics. They expect him to cling close to the middle of the road in his party and to follow the cautious politics laid down by those who preceded him.

Ohira's accession will complete a political cycle that began in 1972 when former prime minister Eisaku Sato left office. Four men - Ohira, Fukuda, Takeso Miki and Kakuei Tanaka - were waiting to replace Sato; all were out of the mold of moderate conservatism. Six years later, after interminable factionalism, all four of them have made it to the top.

Ohira, 68, a bureaucrat-politician, virtually on the premiership yesterday in an upset party primary victory over Fukuda, who promptly withdrew. On Friday he is scheduled to be chosen party president by colleagues in the parliament and next week to be elected prime minister.

The election was essentially an extension of factional party struggles and it underscored similarities, not differences, in the policies of the two men.

Ohira is a beefy, slow-moving, taciturn man who rarely shows anger in public and is nicknamed "Daddy" by his aides. Philisophic, with a streak of fatalism, he takes a modest view of what men of his calling can accomplish.

"The reality of the political world," he once said, "is that it is not all being operated by saintly and noble people." He has also said that government intervenes too much in people's lives and that people in turn have come to depend too much on government.

Like many Japanese politicians, he is a self-made man who followed the road of bureaucratic politics to the top. The son of a farmer from the island of Shikoku, he put himself through college and went immedaitely into the Finance Ministry, becoming an aide to Hayato Ikeda, who later was to become prime minister. Under a succession of governments, he has served as finance minister, foreign minister and minister of international trade and industry.

He varies from the usual Japanese politician in several ways. He is a Christian in a country of Buddhists and Shintoists. He is a Teetotaler in a profession where heavy drinking is common. Unlike most of his contemporaries who occupy leading roles, he is an avid reader who makes one or two trips weekly to a bookstore. He once wrote that he likes to read many books so that he will forget about eating and sleeping.

Ohira is generally regarded as a poor pubic spearer and no one has detected the slightest wisp of charisma. His eyes are heavily lidded, often causing him to give the impression that he has fallen asleep in public. He speaks slowly and monosyllabically and listeners frequently wonder if his sentences will ever end. He has a reputation for making up his mind slowly put sticking to decisions once made.

Ohira's economic views fit him comfortably into the succession of liberal Democratic prime ministers, with one excepttion. He talks frequently of Japan having entered an era of slow economic growth, after nearly two decades of booming prosperity and high-growth rates. Fukuda and his immediate predecessors, Miki and Tanaka, expressed similar views occasionally but Ohira seems more determined to come to grips with the new reality.

Fukuda had promised repeatedly during the past year that Japan would reach a growth level of 7 percent in the current fiscal year, largely to boost domestic demand in order to trim the country's large trade surplus and appease trading allies. Without expressly abandoning that goal, Ohira suggested during the campaign that strict adherence to that goal could cause a new bout with infaltion. That could be taken to mean he may retract or slack down some of the public-service spending that Fukuda had initiated in supplementary budgets.

In defense matters, Ohira, like his prdecessors, would rely primarily on the American umbrella and proceed to make modest but steady improvements in Japan's defensive arms. He has said often that defense must embrace diplomatic and cultural measures designed to immunize Japan from hostilities with other countries. Such phrases are usually taken as dovish code words here.

Fukuda had deliberately set out last January to initiate a broad-ranging debate over defense matters that is still going on. Many took this to mean he was seeking a national consensus for a substantial increase in arms spending sometime in the future. Publicity at least, Ohira took little part in the debate.

On one specific issue he disagreed directly with Fukuda. The prime minister has supported a campaign to draft legislation spelling out how the defense forces should be allowed to react in the event of a national emergency. Critics charged that he wanted to be able to put Japan on a wartime footing. Ohira described the scheme as unnecessary and said the present law is sufficient. He also opposed the idea of revising the constitution to give official recognition to the armed forces.

Ohira has proposed few new ideas that might make his tenure as prime minister a new departure. That may be due to his essential skepticism about government. He once said that, in public service, it is better to "eliminate one evil" than to try to accomplish many "benefits". In his autobiography, he cautioned generally against seeking answers to problems that could make matters worse than they are.

During the campaign, Ohira suggested one major innovation, the creation of "pastoral cities" where people might have greater living space and serenity and proposed government assistance to urban areas limited to 200,000 or 300,000 people.

"I am thinking about creating a community with the emphasis on human beings where people will help each other and will take good care of their inherent culture," Ohira said in interview with the Asahi newspapers.

"I believe it is in line with an age which stresses quality more than quantity.