Go south, where Japan steams
Kyushu is what happens when you take everything backpackers love about Japan, subtract most of the tourists, and add volcanoes. The southern island runs on hot water: entire towns are plumbed with it, streets vent it, and eggs are cooked in it by the roadside. Ten days here after, or instead of, the Golden Route shows you a Japan that still seems mildly surprised to see you.
Fukuoka, the easy landing
Start in Fukuoka, reachable by shinkansen from Osaka or cheap flights from anywhere in Asia. It is a compact, friendly city famous for tonkotsu ramen, and its defining ritual is the yatai: open-air food stalls that appear along the river at dusk, seating eight strangers shoulder to shoulder around a steaming counter. Dinner and a beer at one runs about 2,000 yen and you will not eat alone. Dorms cost 2,800 to 4,000 yen, and the JR Kyushu rail passes (around 20,000 yen for five days, all-island) start paying off immediately.
Nagasaki, two nights
Two hours southwest by the Kamome shinkansen and relay train, Nagasaki folds an enormous amount of history into a small harbour city: the atomic bomb museum, quieter and in some ways harder-hitting than Hiroshima's; the old Dutch trading island of Dejima; hillside streets threaded with Catholic churches and Chinese temples from its centuries as Japan's only open port. Ride the streetcar everywhere for 140 yen a hop, eat champon noodles in Chinatown, and take the ropeway up Mount Inasa at night for a harbour view the locals rank among Japan's three best.
Into the Aso caldera
Backtrack toward Kumamoto, pay respects to its slowly-healing earthquake-damaged castle, then ride the little cross-country train into the Aso caldera, one of the largest on earth. There is a moment when you realise the entire plain of farms and towns you are crossing sits inside the ancient crater rim, and the active cone of Nakadake smokes in the middle of it. When gas levels permit, buses run near the crater edge and its improbable turquoise lake. Guesthouses around Aso town run 3,500 to 5,000 yen and rent bicycles for the grasslands.
Kurokawa Onsen, the splurge that isn't
An hour north by bus, Kurokawa is the onsen town of your imagination: a wooded gorge, lantern-lit lanes, no neon, thirty ryokan along a rushing stream. The genius move is the tegata pass, a wooden disc for about 1,500 yen that buys entry to any three outdoor baths in town. You can soak in a cave bath, a riverside pool and a cedar tub for less than a Tokyo lunch, sleeping at a simple minshuku or the local backpacker guesthouse rather than a 40,000 yen ryokan. December, with snow falling into the hot water, is the dream version.
Beppu, the gonzo finale
Finish across the mountains in Beppu on the east coast, the most productive hot spring city in Japan and gloriously unpretentious about it. Steam rises from drain grates. The jigoku, or hells, are boiling ponds in impossible colours toured for about 2,000 yen, but the real experiences are cheaper: 300 yen neighbourhood bathhouses run since the Meiji era, a sand bath where attendants bury you to the neck in naturally heated black sand for 1,500 yen, and steam-cooked vegetables you prepare yourself at public hell-steamers. Yufuin, thirty scenic minutes inland, makes a gentler half-day if Beppu's rough edges are not your thing.
Practicalities
Buses fill the gaps the trains leave, and bookings matter for the Kurokawa legs. Count on 8,000 to 11,000 yen a day. Spring and autumn are ideal; summer is hot but uncrowded. Carry a small towel at all times. You will be getting in the water constantly, and that is the entire point of Kyushu.
