The portable freezer/refrigerator “PacifiCool” has been available for pre-sale on the Japanese crowdfunding site “Makuake” since September 6, 2021, and is gaining popularity with sales exceeding 5 million yen. The feature of PacifiCool is that it uses vacuum insulation, which is also used in high-end cooler boxes, to increase the cooling power even in an environment without a power source. In Japan, due to global warming, it is not uncommon for summer temperatures to exceed 35 degrees Celsius, and portable refrigerators are becoming increasingly popular for camping.