Japan has a lot of active volcanoes, which means it also has a lot of hot springs. Known in Japan as onsen, these natural baths have brought physical and spiritual refreshment for centuries. They were used in turbulent times to heal wounded samurai, and the peace that followed gave birth to onsen tourism. More recently, new onsen businesses are taking off across Japan. Our expert guest this time is Michio Ishikawa, who has visited over 2,000 onsen. And in Plus One, onsen aquaculture!