The term “Keppyo” refers to the freezing of water surfaces such as oceans, lakes, ponds, swamps, rivers, and waterfalls. In Lake Mashu and Lake Kussharo, where Teshikaga Town is located, “total freezing” occurs around February every year, when the entire lake freezes over. However, in recent years, due to various reasons such as global warming as well as the climate and weather conditions of the year, the total freezing over does not occur every year, and is said to be a miracle that occurs only once every few years.According to Professor Takao Kameda of the Kitami Institute of Technology, who has been studying the freezing of Lake Mashu, Lake Mashu is expected to fully freeze over in 2023 (as of September 1, 2022), based on weather data from the Kawayu AMeDAS station closest to Lake Mashu. If the lake fully freezes over, it will be the first time in two years that Lake Mashu has been completely frozen over, and it is hoped that this miracle will occur in 2023.