For Teiko Watanabe and many other young Japanese women like her, a modest salary and the good things in life are not incompatible.

A $575-a-month clerk in a Tokyo food shop, she loves to travel and buy new clothes. At least once a month, she manages a two- or three - day trip somewhere in Japan. Last summer she spent about a million yen - more than $5,000 - on a 15 day trip to Europe, traveling, eating and shopping her way through France, Italy and Britain.

Her shopping expenses are moderate, compared to other working women in her age group, but Watanabe estimates she still spends about $130 a month on clothes and accessories in Tokyo's department stores and shops.

She is typical of the young Japanese women who work in shops and offices of Tokyo and who are known, collectively, as "the office ladies." Their jobs usually are humdrum and their salaries modest, but altogether they make up one of Japan's richest consumer markets.

Airlines and travel agencies model sales campaigns to reach their pocket-books. Department stores deliberately locate near their offices and stores. Magazine ads are tuned to their tastes and styles. They buy $400 Hanae Mori party dresses or polyster models for $150 and are a growing market for expensive fur coats.

The key is their unusually high disposable income and their penchant for disposing of it. Young, unmarried, often living with their parents, they are able to disburse without pain a large share of the money they earn.

"What they think is, "Now is the time to travel because after marriage it is too late," says Katsumi Takeuchi, manager of research at Dentsu, Japan's largest advertising agency.

As a group, they are a curious anomaly in Japan, where a lot of work and very little play has been the rule ever since the end of World War II, and where even inconspicous consumption has been unfashionable.

Japanese women were first lured into office, shop and factory jobs in large numbers after the war because of the labor shortage. Young women suddenly began making, for them, a large amount of money and they emerged as the only large group that did not desperately need its yen for daily sustenance. Most of them live with their parents until marriage, sometimes but not always chipping in on the rent, and they alone escape paying the high rents or mortgage costs for Japan's expensive housing.

Unlike men of a similar age, they are not bound to a carer ladder and are mainly out for a good time until they marry. Young, ambitious men often refuse even to take company sponsored vacations because it might look bad at the office. The young woman is under no such restraints.

The mere fact that they do take vacations has transformed women under 30 into Japan's most lucrative travel market. While male travelers tend to ply the usual holiday routes to South Korea and Southeast Asia, the young woman heads for Europe and the mainland United States, often spurning the cheap mass package tours to vacation abroad with a friend.

"They want to see the world," says Hisashi Ito, general manager of international passenger marketing for Japan Air Lines.

One survey by JAL shows that overall travel by Japanese men has declined slightly since the oil shock of the early 1970s, but travel for women under 29 has increased since then by 18 percent.

Their clothing tastes run from the routine to the very expensive. In a smart shop in the Shibuya section of Tokyo, where half the customers are young office workers, Hanae Mori silk party dresses go for 75,000 yen, nearly $400, and polyester copies bought for daily office wear cost 29,000 yen, about $150. Half are sold on credit.

Fur coats in Japan were once the fashion only for the rich and middle-aged. Now retailers say the "office ladies" are among their most reliable customers. They buy a third of the fur coats in the Ginza's Mitsukoshi Department Store; 10 years ago it was only 10 percent. They buy lamb, fox and rabbit furs costing an average of nearly $1,600 and sometimes save up for a mink worth a million yen, or $5,200.

The mecca for many is Parco, a chain of stores that rents floor space to chic shops. The company rule is that 60 percent of the merchandise space should be geared for young working women. Tsuji Masuda, representative director of Parco, estimates from surveys that the average office worker spends about $150 a month for clothes and other fashions.

To capture that market, Parco rarely advertises specific products but tries to sell a total life style - the smart, well-dressed young woman who goes out in the world to travel and hold down a job. Parco's fall campaign is based around French actress Dominique Sanda, who is seen in ads dressed in men's formal wear and smoking a cigarette, a style far too daring for Japan's traditional department stores.