But Monica had no idea of what awaits foreign prostitutes in Japan: debt bondage, sometimes violent working conditions, so-called fines imposed by pimps or brothel owners for any attempt to escape, and no help from authorities.

``The reality is different once you arrive - it's much harder than you ever imagined,'' said Monica, 31, a Colombian single mother who still works the Tokyo streets.

The thousands of cases like Monica's are at the center of a mounting crackdown on human trafficking in Japan following the country's placement on a US watchlist last year. Japan was again cited for trafficking in a US human rights report last month. Affluence and a lack of laws against sex trafficking have combined to make Japan one of the world's top destinations for women like Monica.

In the popular imagination, human trafficking involves women who are kidnapped or otherwise tricked into working as prostitutes. But experts say such cases are rare in Japan.

More common are women who come voluntarily but encounter slave-like conditions - and trapping debts - on arrival.

``The Japanese human trafficking problem is the sex industry,'' said Kazuo Inoue, an opposition Democratic Party lawmaker and anti-trafficking activist who says a crackdown needs to address the root cause, demand stoked by loosely regulated red-light districts.

Tokyo is moving to clean up its act. The government is expected to pass a law this spring to make trafficking of foreign victims into Japan a criminal offense for the first time.

Authorities also have moved to tighten visa requirements for ``entertainers'' - suspected to be legal cover for foreign sex workers.

``We are in the process of drawing up the necessary measures to effectively battle this,'' said Masaru Sakamoto, from the cabinet office overseeing a government anti-trafficking plan released in December. ``I think once those are in place, the fruits of our efforts will become more evident.''

Critics, however, are still waiting to see if Japan is also serious about protecting victims. Japan has long treated women like Monica as accomplices to the traffickers who bring them here, deserving of few rights as sex workers and illegal migrants.

Monica was a single mother - she had her daughter at 13 - from a poor, violent barrio of Bogota when she was approached by a broker with the offer of sex work in Japan, something that would pay enough to buy her daughter a better future back home in Colombia.

``No one comes because they want to do this work. But we choose to because there's no better option. We want to get out - at any cost,'' said the petite redhead.

After arriving in 1993, Monica was slapped with a debt of five million yen (HK$374,000) - much larger than she'd been led to believe - and warned of reprisals against her family if she tried to escape. Minor infringements, including illness, can inflate that debt, she said, and women suffer a brutal physical toll in serving dozens of customers a week, with no days off, to get rid of the debt.

She was able to repay her debt in several months since Japan's economy was then faring better. But she said others now aren't as lucky, with some finding themselves in bondage for more than a year amid ever-increasing fines for various infringements.

Statistics on women trafficked in Japan are hard to get. Activists estimate more than one million may have come since the early 1980s.

The Switzerland-based International Organization for Migration calculates that Japan's sex industry hosts about 150,000 foreign workers.

The Philippines, Colombia and Thailand are the top source countries, says a recent report by the International Labor Organization's Japan office, although anecdotal evidence on the street points to a surging number of Russians, Koreans and Chinese as well.

The sex industry has long been treated with leniency: red-light districts have openly thrived from the patronage of legitimate businesses.

Critics have repeatedly alleged ties between traffickers and law enforcement, from immigration officers taking bribes to allow prostitutes into the country on fake passports, to police who return escaped, abused sex workers to their captors. Those allegations are denied by the National Police Agency.

Kinsey Alden Dinan, a Columbia University researcher and trafficking expert, says the Japanese government has done little to safeguard sex workers' rights and well-being or ensure they have ways to exit the industry.

``When there's clearly a demand for these people to work in your country, you have an obligation to work out a system that they can do it in legally and safely,'' she said. ``It's easier to deport them than to deal with them.''

Sakamoto of the cabinet office pointed out that the government's anti-trafficking plan would include some counseling for prostitutes and plans to postpone immediate deportation to encourage victims to testify and cooperate with authorities. But it's expected only a few would qualify since the government does not recognize those who have willingly entered the country for unauthorized labor as victims, regardless of the ensuing conditions.

``I don't see a clear plan to protect and support victims,'' said Yoko Yoshida, a lawyer and director of the Japan Network Against Trafficking in Persons, calling for the anti-trafficking plan to include medical attention, legal advice and job training for victims.

Japan's fabled wealth has long drawn the hopeful, and many believe turning them away could prove difficult.

``Entertainment'' visas, intended for musicians, dancers and other entertainers, are issued to 80,000 Filipinas each year. But critics call the visas a front for sex trafficking, saying most women who get the visas end up working illegally as strippers, hostesses and prostitutes.

Tokyo tightened visa requirements this week, which is expected to dramatically reduce the number it issues.

Yet those plans threaten a US$400 million (HK$2.12 billion) flow in annual worker remittances sent home by Philippine citizens in Japan, and last month Foreign Secretary Alberto Romulo came to Tokyo to seek leniency for entertainers already in Japan.

Chaturont Chaiyakam, a consular official at the Thai Embassy in Tokyo, estimates that of 15,000 illegal Thai migrants in Japan, roughly 6,000 are in prostitution.

Flipping through stacks of victims' affidavits collected by his embassy, Chaiyakam said it's not unusual for those sent home to Thailand to get smuggled again into Japan.

``There is still demand, so people want to come.''

Pointing to another problem, Chaiyakam said 4,000 children of Thai victims are estimated to be living in Japan effectively stateless. With no registered fathers and no documents, they can't enroll in public schools and wander the streets waiting for their mothers to get off work.

Monica said her dream of a new life can never be realized in a country that offers women like her a place in its sex industry but no place in larger society.