(FORTUNE Magazine) – When he commutes across Tokyo to classes, university student Ryoichi Mizutani, 18, carries his books in a $100 black Valentino shoulder bag and his subway pass in a $60 Louis Vuitton wallet. Naomi Matsuoka, 21, a senior at prestigious Waseda University, orders Budweiser or Heineken in restaurants instead of local brands ''because of the ambiance'' of imported beer. For a snack she likes the designer ice cream at Dipper Dan, Baskin-Robbins, or Haagen-Dazs.

Instead of grumbling about closed Japanese markets, Western companies should take aim at Japan's young consumers. These Juppies crave American and European imports, and they have plenty to spend. Getting them hooked now will pay off in the future too. Within ten years the generation born after 1955 will make up 42% of Japan's consumer market, according to a Sanwa Bank study. Japanese youth are heavy on hedonism and light on traditional Confucian values of frugality and hard work. Dubbed the shinjinrui, which means ''new breed of man,'' they are more individualistic and creative than their elders. Their parents scrimped and saved to rebuild after the war, but they save little and spend extravagantly on what they want. A new phenomenon in Tokyo is the ''BMW pauper,'' a young Japanese who lives in a shabby room and possesses not much else but his BMW. Indulgent parents give kids generous monthly allowances plus cash gifts at New Year's. Many students work after school too and spend much of what they earn on themselves. Naomi Matsuoka says she earns about $340 a month tutoring high school students in English and pockets another $340 in allowance, which ought to buy a lot of Haagen-Dazs ice cream. Tokyo teenagers have disposable incomes averaging $2,900 a year, according to Marplan Japan, the market research subsidiary of the McCann-Erickson Hakuhodo advertising agency. American products, which older Japanese sometimes view as shoddy, are in particular demand with the shinjinrui. ''If I were selling U.S. goods to the young overseas, I'd rather sell in Japan than in France or Italy,'' says Robert Wilk, an American who is managing director of Marplan Japan. Along with U.S. fast-food and ice cream chains, a few American companies have already cashed in. San Francisco-based Levi Strauss makes jeans and other items in Japan. Its ad campaign, ''Heroes wear Levi's,'' featured images of James Dean. Another California-based company, Tower Records of Sacramento, is the only foreign outfit in the retail record business. After the U.S., the Japanese record market is the biggest in the world. Tower imports records from the U.S. and sells them for 30% to 40% less than Japanese competitors. Japan accounted for about 5% of Tower's worldwide revenues last year, or $12 million. Cashing in on the fitness craze is entrepreneur Griffith Frost, 29, an American who went to Japan as a student and stayed. He has a license to manufacture and sell Soloflex exercise equipment. Sales hit $4 million in 1986, Frost's first full year in the business. Students' fascination with America is an opportunity for travel companies. Young Japanese are among the world's greatest overseas trekkers. Last year travel to the U.S. mainland by Japanese honeymooners doubled. ''Many older Japanese are ambivalent about the U.S., since it's an enemy turned friend,'' says Joseph Precker, an American psychology professor at Tokyo's Sophia University who is also a marketing consultant. ''But to the young, the U.S. is a paradise.'' Ryoichi Mizutani, the fellow with the Valentino shoulder bag, is an aspiring dancer who dreams of studying in New York and of dancing on Broadway. But tours have to be geared to the new generation. Marplan's Robert Wilk suggests trips to prestigious American colleges for the education-minded or a ski trip that would offer Japanese a chance to meet their U.S. counterparts at, say, the University of Colorado. Lots of other opportunities exist. Though fast food has caught on, such snack foods as pretzels and dips for chips are still hard to find. Western- style breakfast foods should do well in Japan, particularly since housewives are returning to work in increasing numbers. Mail-order marketing is just getting started. Less than 1% of retail business is done by mail in Japan, vs. about 10% in the U.S. One surprising hit from the U.S.: stationery. Students especially like American notebooks and binders. Says Keiko Shimizu, 26, a marketing planner at Sony who spent some of her growing-up years in New York: ''Japanese students are fascinated with the Ivy League image. They feel American when they buy American stationery.''