Japanese man arrested for allegedly hacking Pokémon game to sell custom monsters

Japanese police arrested a man after finding evidence that he illegally tampered with save data for the Nintendo Switch games Pokémon Scarlet and Violet, which he used to create custom characters that he sold on an online gaming marketplace.

According to machine translations of stories at NHK and the Asahi Shimbun, the Kochi Prefectural police arrested 36-year-old Yoshihiro Yamakawa on April 9th after cyber patrol officers caught him selling the characters online. Yamakawa, who used an online tool to modify the game’s save data, was arrested under suspicion of violating a Japanese law known as the Unfair Competition Prevention Act.

The police report, according to both outlets, states that the Japanese police cyber patrol caught Yamakawa in the act of taking orders. Yamakawa offered deals for hard-to-train and rare monsters, such as “6 Pokémon for only $30,” on an online platform that sells game assets and characters.

As we noted in our review of the games in 2022, battling and collecting monsters is an unsurprisingly major focus, and both titles were jam-packed with new, never-before-seen monsters. Players go on increasingly difficult raids to capture exotic and hard-to-find monsters, with the goal of training, battling, and, in some cases, even breeding them. It turns out some players covet rare pokémon enough to buy them on the black market. 

Enough demand, in fact, that this isn’t the first time this has happened. In a seemingly parallel case back in 2021, Japanese police arrested a man under the same law for illegally altering the save data of Pokémon Sword and Shield. As Polygon noted in its account of the incident, hacking into the save data of Pokémon games became so rampant among cheaters that The Pokémon Company began cracking down on the practice.

Between December 2022 and March 2023, Yamakawa allegedly sold his custom monsters for up to 13,000 yen each, which is roughly the equivalent of $85. Although Yamakawa reportedly confessed to the charges, telling officers “I did it to earn a living,” the case is still under investigation. Police suspect that Yamakawa’s total profit amounted to millions of yen (equivalent to anywhere between tens and hundreds of thousands of dollars), and an investigation is underway.