Naked girls still beckon from the magazines read with nonchalant aplomb by salarymen headed home from the office on the crowded subways.

But Japan is hoping a new law on pornography and child prostitution will help it shed its image as one of the most licentious capitals in Asia.

The law, which took effect in November, makes it a crime to distribute child pornography or solicit minors for sexual purposes either in Japan or abroad, where the Japanese have a long and sordid reputation for their "sex tourism" and recruitment of Asian women to work in Japanese brothels.

The Diet, Japan's parliament, backed away from making possession of pornography a crime--leaving untouched the titillating magazines and adult comics read openly here, many with explicit pictures of young-looking girls.

But the message already is having some effect: The largest daily newspaper, Yomiuri Shimbun, announced this month it would no longer accept advertising from two racy weekly magazines. The leering ads, with suggestive models and bluntly sexual language, had been regular and lucrative advertisements for the daily newspaper.

The newspaper said it was making the move because of complaints "both inside and outside our company" about the sexual content of the ads.

While Yomiuri Shimbun did not mention the new law, it is clear the legislation--passed after three years of debate--is helping set a new tone for Japanese sex-related consumerism.

"What we are doing is to punish what was not being taken seriously in the past in this country. It requires a change in the Japanese public's way of thinking," said Mayumi Moriyama, the chief sponsor of the legislation in the Diet.

"In Asia, Japan has the worst record of child sexual exploitation," Moriyama told an Asian-Pacific conference on human trafficking in Tokyo last week. "It is said that 80 percent of the child pornography distributed in the world is made in Japan."

And Japan's unrepentant attitude about the subject has sullied its image, she said, evidenced by a Time magazine cover story last year entitled "Japan's Shame." "It is a grave situation when Japan's dignity and honor are questioned" because of sex, Moriyama said.

The statute makes it illegal to pay for sex with anyone under age 18, as well as to traffic minors for sex, and to produce, distribute or sell child pornography.

Significantly, the law applies to Japanese whether they are in or outside the country, a sweeping move that put a quick chill on advertisements for "sex tourism" to Korea, Thailand, the Philippines and other Asian countries.

Toshinori Kanemoto, head of the international criminal affairs division of the National Police Agency, said since the law took effect in November, 20 Japanese men have been arrested for engaging in child prostitution and 22 for violation of the pornography provisions.

The easy flow of people and pornography across national borders is "the dark side of globalization," Kanemoto said.

The Japanese have been sensitive to their image on this subject, but slow to impose tough regulations. The new law was finally enacted after public outrage erupted last year over stories about the fad of "arranged dates" in which older men paid for liaisons with schoolgirls.

But some of the activity has gone underground. Experts say that while Japanese sex tours have decreased because of the publicity, the number of Asian women imported to Japan for prostitution has increased.

"Japan is a destination country for trafficking in persons," acknowledged Shozo Azuma, senior state secretary for foreign affairs. But Yukio Machida, head of the Justice Ministry's immigration bureau, said it is difficult to determine if women are entering Japan to join the sex trade.

"They appear to be tourists. It's very difficult to identify them," said Machida. He said more than 4.9 million foreigners visited Japan last year.

The Foreign Affairs Ministry sponsored last week's conference, in part to showcase the new law and its efforts to curb sex trafficking. But it was clear in the comments of one panelist, Helena Karlen of a Swedish organization for the protection of children, that Japan's reputation needs much work.

"My experience from several visits here is that people are quite indifferent to the problem," she told her hosts. "I was so shocked every time I came to Japan and found child pornography readily available." Brandishing a book about the death of a Filipino girl in the sex industry, Karlen said, "I would like to have every Japanese person read it."

"I would say there has been some improvement," the Japanese moderator, Hideaki Ueda, finally demurred. He noted that, at least, the racier weekly magazines "are no longer available in Japanese airliners."