The training film opens with a conservatively dressed man, an elastic-faced mime with doleful eyes and eyebrows that bounce like rubber balls, approaching a kimono-clad housewife in front of her home in a conservative Tokyo suburb. He asks for a few minutes of her time. She politely tells him to buzz off.

The scene depicts a routine rejection for a foot soldier in Japan`s huge army of door-to-door automobile salesmen.

More than 75 percent of the new cars purchased in Japan are sold by men

(and a handful of women) who make their living thumping thresholds and pounding on portals. The country`s automobile manufacturers reaped $26 billion from door-to-door sales of new cars in 1984.

This training film is one of many instructional aids produced by Tokyo Toyopet--the capital city division of the giant Toyota Motor Sales Co. Ltd.-- to help prepare salesmen for some of the problems they will face when they start walking their beats. A 31-year-old company, Tokyo Toyopet employs some 1,200 salesmen who regularly and methodically circulate among the city`s 11.5 million residents, peddling cars as fervently as the Fuller Brush Man hustles lint remover or the Avon Lady pushes perfume.

They must be effective. Tokyo Toyopet is the top dealer among 318 Toyota sales companies around Japan, signing contracts for almost 71,000 new cars in 1983 and more than 75,000 in 1984.

Although door-to-door selling may appear a haphazard way to do business, Tokyo Toyopet has it down to a science. The best time to hit a potential new- car buyer, the company judges, is just after his car has completed its

''shaken,'' a mandatory inspection when the auto is three years old.

''We have found that that is when owners are most likely to make a decision about a new car,'' says Tokyo Toyopet spokesman Shoichi Miyata.

''That is the time they are most prone to say they are thinking about trading in their old vehicle.''

Armed with a ''shaken'' list and a computer printout of all Toyota owners, a Tokyo Toyopet salesman starts knocking on doors. Each salesman has a rigidly defined area of responsibility, its size depending upon population density. In central Tokyo, it may be only a square block.

Lugging a black sample case in the best Willie Loman tradition, a Tokyo Toyopet salesman, wearing the ubiquitous dark suit and a big smile, visits some 30 households a day. (An experienced one has to make only half that number of calls; he knows his area better and is more familiar with his potential customers` habits.) If no one is home, the salesman doesn`t hesitate to call on the potential buyer at his workplace--a practice apparently condoned by Japanese employers.

The salesman can expect a warm reception from a Toyota owner. Brand loyalty is extremely high in Japan, and Tokyo Toyopet estimates that 90 percent of Toyota drivers stick with the company when buying new vehicles. Among non-Toyota owners, Miyata says, only about half are willing to listen to a pitch.

The first thing a salesman proposes, if the door isn`t slammed politely in his face, is an evaluation of the customer`s car--the at-home equivalent of driving to a dealer for a trade estimate. Tokyo Toyopet has found that one out of 10 will accept the offer; three of 10 who do will decide to upgrade.

Then, from a satchel crammed with catalogues, brochures, insurance questionnaires and installment-payment forms, the salesman probably will proffer for the customer`s inspection a well-made, toy-size model on one of the popular new cars. To the miniature-conscious Japanese, this is better than a visit to the showroom.

A good salesperson will sell 200 cars a year this way--almost four a week --and will make about $45,000. A relative neophyte, perhaps a bright young salesperson with about three years experience, can expect to bring home almost $17,000, roughly as much as a corporate junior executive with three times as much tenure.

The spectacular success of direct selling is reflected in ad campaigns. When Tokyo Toyopet runs a spot, for example, it doesn`t urge potential new buyers to hurry down to the showroom to slam the doors and kick the tires on the latest models. Be patient, the company suggests. A salesman, or one of the company`s 10 saleswomen, will be along by and by.

Radio is overwhelmingly the advertising medium of Tokyo Toyopet`s choice. Newspapers and magazines are impractical because they circulate nationally and Tokyo Toyopet sells only in Tokyo. Television is too expensive. That leaves radio, which has the additional benefit of being exceedingly popular. Listening to the car radio is a favorite pastime in Tokyo`s horrible traffic jams. What better opportunity, car manufacturers reckon, to get a potential customer thinking about trading in his old, uncomfortable vehicle?

Automobile advertisements in Japan are not as product-oriented as they are in this country. ''Our intention is not to sell cars as such, but to sell the company image,'' Miyata says. ''Our campaigns are aimed at helping the activities of our salesmen, not at attracting customers to the showrooms.''

Miyata hints, however, that this policy is subject to revision, or at least modification. More Japanese women, like their counterparts in the West, are working away from the home, and there often is no one to answer when the salesman comes knocking.

But cars are only part of it. In Japan, everything is sold door-to-door. The Yano Research Institute estimates that direct sales, excluding

automobiles, totaled $13 billion in 1984. Only the United States has greater volume. If the current rate of growth continues, door-to-door sales in Japan will rise by 26 percent in 1985, to $17 billion.

In the land of the rising sun, door-to-door sales people have whatever you want. Need a new broom? Help will come before the dust settles. Wondering what to do with your paycheck? A representative from one of the city`s numerous banks will gladly accept a deposit. Feeling the urge to invest in the stock market? A securities firm will send someone around. Cosmetics? No problem. Insurance? You`re covered. A condo? You can move in next week.