• Japanese police have made the first arrests under a brand-new law banning online casino advertising, detaining two individuals for promoting an illegal gambling site.
• The affiliate website, named Onkaji Hissho, allegedly facilitated ¥70 billion (approx. €470m) in bets on an unlicensed, overseas online casino, earning its operators substantial commissions.
• The arrests come just one day after the new Japanese law, which prohibits all forms of affiliate marketing for online gambling, came into force on 25 September.
• Online casino play is illegal for residents in Japan, but a massive black market exists, estimated to be worth over €8.3 billion in annual wagers.
• This swift enforcement action is a powerful signal of the Japanese government’s new, aggressive stance against the entire marketing ecosystem that supports illegal gambling.

A Swift and Decisive Enforcement Action

Authorities in Japan have wasted no time in enforcing a tough new law designed to cripple the promotion of illegal gambling, making their first high-profile arrests just one day after the legislation came into effect. Gifu Prefectural Police have detained two individuals, including a company executive named Hisato Yonezawa, for allegedly operating an affiliate marketing website that promoted an overseas online casino to Japanese players.

The move is a powerful “shot across the bow” to the entire black market supply chain and signals a new era of aggressive enforcement against illegal gambling in the country.

The ‘Onkaji Hissho’ Operation

The investigation targeted a website named Onkaji Hissho, which police say promised “guaranteed wins” to lure customers. The site allegedly gave users detailed instructions on how to register and play at a Curacao-licensed online casino.

The scale of the operation was significant. Investigators claim that over a four-year period, the website funnelled approximately 670 users to the casino, who then placed bets totalling around ¥70 billion (approx. €470 million). The website’s operators are alleged to have received substantial commissions from the casino based on the total volume of bets placed by the players they referred. The police investigation also noted that transactions involving cryptocurrency were part of the operation.

Japan’s New War on Gambling Ads

These are the first arrests to be made under Japan’s new law on online gambling advertising, which officially came into force on 25 September 2025. The law was passed in June and creates a wide-ranging prohibition on the promotion of any online gambling services to Japanese residents. The ban explicitly covers:

• Affiliate websites and ranking platforms.
• Promotional links and direct advertising.
• Celebrity and influencer endorsements.

Social media platforms and websites are now also required to remove any gambling-related ads when instructed to do so by the authorities.

A Clear Warning to the Black Market

While playing at an online casino is illegal for residents in Japan, the country has a massive and thriving black market. It is estimated that 3.37 million Japanese people engage in online gambling, wagering an estimated ¥1.24 trillion (approx. €8.3bn) annually on offshore sites.

This first, swift, and high-profile enforcement action is a clear warning from the Japanese government. It signals a strategic shift from simply trying to block operator websites to actively dismantling the entire marketing and affiliate ecosystem that fuels the illegal gambling market. For any affiliate marketer or promotional website considering targeting the lucrative Japanese market, the risks have now increased exponentially.