TOKYO -- Seiko Watanabe, 25, conceded with a laugh that her parents think she's strange. Her relatives wonder why she's not getting married. Her friends worry about her dropping out of their lives.

Watanabe, an occupational therapist, is in training to spend two years in the Solomon Islands as a Japan Overseas Cooperation Volunteer -- Japan's equivalent of the Peace Corps. In a nation where young people are supposed to get on a life track at an early age and never step off, her decision strikes many as peculiar.

But if Watanabe and her colleagues-in-training are nonconformists in a society that prizes conformity, they also reflect a gradually increasing acceptance of diversity, individual choice and international exchange. Next month, the Japanese program will celebrate its 25th anniversary, and its officials and volunteers say the country is far more accepting of their mission than it once was.

Kei Kitamura, 33, a physical therapist who will soon be dispatched to Tonga in the southwestern Pacific, said he considered going overseas 10 years ago. "The atmosphere was so different then," he said. "My friends said, 'If you go now, I may never you see again.' It was this tragic, unusual, dangerous kind of thing. Now everyone accepts it. It's natural. It's a good thing. It's no big deal."

To be sure, the Japanese program remains small compared to the Peace Corps: about 9,000 volunteers dispatched since 1965, compared to more than 120,000 Americans since president John F. Kennedy inaugurated the U.S. program in 1961. About 2,000 Japanese are now serving overseas in 45 developing countries, compared to about 6,000 U.S. Peace Corps volunteers.

And the program, not surprisingly, is distinctly Japanese in certain ways. The 326 young volunteers now training in Tokyo and at a second center in Nagano all wear uniforms, like any good Japanese employee: khaki suits and white shirts with somber blue and red neckties for men and bows of the same colors for women.

When Kitamura departs this summer, like many Japanese employees sent abroad by their companies, he will leave behind his family -- his wife and three children, aged 6, 3 and 1 -- rather than expose them to the risks of foreign living. Kenshi Kan, 28, a high school science teacher preparing for assignment in Ghana, has one main worry -- that he will leave his fellow teachers with extra work, particularly in intramural sports, during his two-year absence.

Moreover, the program reflects the modesty of Japanese foreign policy, which since the nation's ill-fated imperial adventures before and during World War II has shied away from anything smacking of missionary fervor. While U.S. Peace Corps volunteers were initially envisioned chiefly as ambassadors of democracy and American goodwill, the Japanese program emphasizes technical expertise -- men and women, up to age 40, who can bring practical experience in fields as varied as telephone-exchange repair, forestry and chicken sexing.

As Japan's cultural influence grows with its economic power, however, that emphasis is shifting somewhat. More and more nations now want Japanese-language instruction, and 25.3 percent of current volunteers are working on the cultural and educational side, compared to 18.9 percent of all previous volunteers.

The program has grown in recent years but still swims against the tide of Japanese living patterns in many ways. In some Japanese companies, taking a two-week vacation can damage a career, never mind two years. Children who spend a year abroad with their families sometimes never fit back in.

"Taking a year off" for students here normally means a year of cram schools to prepare better for university entrance exams, not a trip around the world. A male college graduate is expected to go straight to the company with which he will likely spend his working life, while a woman is supposed to marry at 25 and drop out of the work force to raise children.

To some extent, Japanese volunteers are seeking to escape that lock-step mentality. "Sometimes they feel they can't express themselves fully in Japan, so they want to challenge themselves abroad," said Kyosuke Takaoka, a spokesman for the program. "They're tired of being small cogs in a wheel."

Kitamura said he wants the experience so he can gain -- and pass on to his children -- a wider sense of values than he can find in Japan, where many people think "it's really important just to have more and more money."

Watanabe, who spent the past three years helping severely brain-damaged children, said she was dismayed by the Japanese tendency to hide the handicapped and be ashamed of them. She said she wants to learn how other nations' attitudes differ. Kan said he simply wants to experience something different from Japan, while helping another country.

All of them expect no trouble integrating themselves back into Japan. Returnees used to have trouble finding jobs, Takaoka said, but that is far less true today. "There's been a big change over time," the spokesman added. "Youngsters have diversified, and companies have to adapt to that."

Watanabe, too, said she expects no ill effects. Asked what she hopes to do when she returns from the Solomons, she laughed again and said, "Get married."