The thermal resort of Shibu Onsen, a steadfastly old-fashioned spa resort in the Yokoyu Valley, is our preferred base for visiting the famous Snow Monkeys, who live in and around a steaming pool at the Jigokudani Monkey Park, a bus ride further up the valley. The macaques can be viewed year-round, but are at their most photogenic between November and February, when a thick covering of snow carpets the ground, and steam swirls evocatively from the dark-green waters of their pool.