Kyoto Prefectural Police arrested unemployed 26-year-old Hayato Kato, who lives in Karuizawa, Nagano Prefecture, on 27 January 2026 on suspicion of violating Japan’s Narcotics Control Act.[1] According to the prefectural police, in November 2025 Kato heated cannabis plants at his home in Karuizawa, extracted the illegal compound THC, mixed it into unsalted butter, and then made 8 sweet potatoes for profit.[1]

Kato had been selling the sweet potatoes for 6,500 yen each on the messaging app Telegram, which he used because of its secrecy.[2] Kato had already been arrested and charged for profit-motivated possession of cannabis and other offences, and this new charge emerged from the same investigation.[2] In interrogation Kato denied the charges, saying the items were not made by him and that he had no profit motive.[2]