"There is a possibility that a lack of awareness about illegality encourages people to use online casinos," an NPA official said.

The police conducted the survey on how online casinos, which are blamed for causing addiction and other problems, are being used in the country for the first time. It was conducted from July to October last year, with 27,145 people between the ages of 15 and 79 giving answers.

In the survey, 2% of respondents said that they currently use online casinos, while 3.5% said that they had used such gambling sites. The findings suggest that there could be an estimated 1.97 million active users of overseas online casinos in Japan and 3.37 million people in the country who have used them at least once, according to the NPA.

About 60% of respondents said that they knew of online casinos. The proportion of people who had actually accessed casino sites came to 4.6%, and three quarters of them had gambled on the sites, according to the survey.

The annual amount of money spent on online casinos averaged some ¥630,000 per person.

The proportion of respondents who were unaware of the illegality came to 39.8% among those who had gambled using online casinos and 43.8% among those who have never gambled on them.

About 60% of respondents who had used online casinos said they were aware of their gambling addiction. The survey also found that the proportion of people who ended up borrowing money to spend on online casinos stood at 46.2%.

A separate NPA survey of 40 overseas online casino sites believed to target Japanese users, conducted between August last year and January this year, showed that only two of them clearly state that participation from Japan is prohibited. Eight sites were available only in Japanese.

Among the 40 sites, the NPA found that for 20 sites over 90% of users accessing them were in Japan.

“They are clearly targeting people in Japan,” a senior NPA official said.

All the 40 sites are being operated under a foreign license, meaning they are not subject to Japanese law. About 70% of them were granted a license on the Dutch Caribbean island of Curacao, according to the NPA.

Some sites even advertise that they are a legal operation. “It makes sense that people might believe gambling is legal,” the NPA official said.

Many who run online gambling sites abroad are working to expand their Japanese clientele list by creating sites that are in Japanese.

Techniques the sites use to lure people in Japan into gambling on them include not clearly stating that online gambling is illegal, using celebrities on billboard ads and offering a “free trial version” that requires no money.

In the NPA’s survey, they found 24% of those who have used such gambling sites started off using the free version, which “acts as a gateway to illegal activities,” an NPA official in charge of the survey said.

The NPA is considering pressuring the sites to stop using celebrities in advertising by saying it amounts to the crime of aiding and abetting.

Various sites that compare online gambling services are also spreading the false idea that gambling is a legal gray area in Japan. Relevant government agencies are considering coordinating to request that sites remove such information.

Police are also working to expose the tokuryū groups, or quasi-gangsters, whom they believe are working behind-the-scenes at such sites.

Last year, a record 279 people connected to such groups (provisional figure) were arrested in relation to online gambling sites.