The man is specifically accused of smuggling roughly 190 kg of stimulants hidden in hot-water tanks when they were shipped from Guatemala to Narita Airport on 14 July 2024. The substances were disguised as insulation materials that coated the tanks. The stimulants were uncovered during a customs inspection, and the man was arrested on the spot when he visited a location in Tokyo to pick them up on 2 September. He was indicted on 11 October. According to the Narita Branch Customs, a total of 12 cylindrical hot-water tanks, each measuring some 165 centimetres long and roughly 40 cm in diameter, were used for the smuggling. Bags each containing several hundred grams of stimulants were put in the gap of the double-layered tanks to make them appear as insulation materials.