I checked the Iwata City official website's waste sorting page and the attached PDFs (Waste Sorting Guidebook, Waste Sorting Classification List), but automatic analysis of the PDFs could not definitively extract relevant descriptions for gas cylinders (cassette cylinders, etc.). Therefore, the following are key points and precautions (to be confirmed) for handling them at this time. 1) Cylinders with remaining contents are highly likely to be classified as hazardous materials. Do not dispose of them as regular household waste. 2) Even when empty (contents fully used), classification (e.g., non-combustible waste, metal items) varies by municipality's guidebook. Always check the relevant page in your municipality's waste sorting guidebook or contact the Waste Management Division (Waste Management Division Phone: 0538-37-4812). 3) Do not puncture the cylinder or attempt to vent the gas, as these actions are dangerous. Only dispose of cylinders according to your municipality's designated method. 4) The city may not collect or process large household appliances or commercial gas cylinders. Consult the retailer or a specialized collection service. Please update the sorting category (combustible/non-combustible/recyclable/bulky, etc.) and specific disposal method once official information is confirmed.