Japan, due to its geological features and being a country made up of islands, is blessed with thousands of hot springs across the archipelago. Onsen is Japanese for hot spring. Technically, in Japan, a hot spring cannot be called an onsen unless it is over 25-degree Celsius that contains a defined level of natural mineral components. There are over 30,000 naturally occurring hot springs in Japan. Hot springs are formed by the heat and gasses of volcanic magma, wherein rainwater reaches the reservoir and comes in contact with volcanic gasses rich in minerals. It is said that the geothermal mechanisms...