Early each spring, the magnificent Mount Aso region in Kumamoto Prefecture opens its sightseeing season with a bang in the rituals of the Aso Fire Festival, and giant characters for “fire” are blazed into the area’s hills.

Its craggy peaks and countless gurgling hot springs shaped over millions of years by the volcanic activity of Mount Aso, give Kumamoto Prefecture its nickname of “Hi no Kuni (fire country).”

But the region is no less famous for its abundance of pure water. The city of Kumamoto has long been described as a “kingdom” of forests and water. While the city has grown and the forests somewhat retreated, naturally formed underground water reserves still supply most of Kumamoto’s 670,000-odd population. The city’s water has been rated among the purest and best-tasting in the country by the Ministry of Health and Welfare.

Much of Kumamoto’s water wells from and is purified by underground reserves carved by the volcanoes of Mount Aso, and the lush highland forests that help trap the water. Kumamoto is the only prefecture beside Toyama to have as many as four of Japan’s official best 100 meisui (drinking-water mineral springs). (Incidentally, neighboring Oita Prefecture has three of the country’s best 100 springs, also derived geologically from Aso.)

You can visit each of these springs, and even take their mineral water home in bottles for free, or for a minimal cost. The water is pure enough to drink as it is. One of Kumamoto’s meisui, Todoro, is outside the city itself, and Shirakawa and Ikesan are in the Aso region.

Still, none rivals the exquisite Kikuchi Gorge and River in the northwest of Mount Aso’s mountainous outer crater, surrounded by breathtaking unspoiled forest. Lush elm, camphor and maple trees cover the steep hills and mossy crags that tower 100 meters above the Kikuchi River, and turn brilliant shades of red and gold late each October. Kikuchi Gorge is one of the few meisui sites that is a river; most meisui are springs. Because the Kikuchi River’s source is 800 meters above sea level, the water is marvelously cool year round — 13 C even in summer. Just wading knee-deep in the river will numb your feet within a few minutes.

There’s a 30-minute trail through the protected national forest around the gorge, and a bird sanctuary, home to about 60 different species. Its cool, forested canopy and constant waterfall spray make Kikuchi Gorge a popular destination during hot weekends in summer, when traffic can back up several kilometers either side of the narrow road leading there. Start early, or go on weekdays.

East of Kikuchi Gorge via the road along northern Aso’s spectacular outer crater is Ikesan Suigen. This lovely spot is surrounded by 200-year-old trees, and watched over by a small stone statue of a water god. Many other springs in the Aso region have Shinto deities or shrines attached, and their holy waters are used for making wishes, blessing newborn babies and in agricultural rites.

Around 30 tons of water pour out of Ikesan Spring every minute. Its excellent 7.1 pH reading and rich mineral content has proved very marketable, and the water is sold under the Ubuyama label. It’s also used in the Kyushu boutique beer, Ginga Kogen.

You can’t swim here, but if you head to nearby Higotai Park, you can splash in a mountain stream and walk to another magical spring nearby: the less-famous and less crowded Yamabuki Suigen.

On the south side of Mount Aso is Shirakawa Suigen, where about 60 tons of crystal-clear water pour into an immaculate, pebbled pond every minute. Shirakawa’s water is marketed around Kyushu under the Hakusui label. If you mistime your visit, you’ll share the spring with hordes of daytrippers busily hauling jugs of water away to their cars. Find solace instead at peaceful Meishin Park nearby, an intimate garden which also has a small spring.

Road signs almost anywhere in the Aso region point not just to its 1,500-plus mineral and hot springs, but also to dozens of rivers and waterfalls. A detailed map or a quick search on the Internet will give you some ideas. Oguni in northern Aso has several pretty falls, including Kappa Falls at the open, sunny Yusui Gorge. A shallow river gushes through the gorge, its smooth volcanic rocks forming a natural slide that kids whizz down on all day. There are a number of walks around the gorge and it never feels crowded.

Aso has long been associated with relaxation and recovery, and its oldest inns and hot-spring establishments date back to the late 1800s. These days the million-plus visitors Mount Aso sees each year are also lapping up its newer treats, from golf and horseback riding to eating ice cream, yogurt and steak at Aso’s many dairy farms. Such development, in fact, has boomed to where it may be overusing the area’s resources — including its water.

As yet, few guidelines have been established for the area’s better use, and those heading out to enjoy Aso’s delightful late summer are simply asked to keep the peace and take their trash home. With better monitoring, more reforestation and more responsible tourism, Mount Aso will remain a kingdom of fire and water.

In line with COVID-19 guidelines, the government is strongly requesting that residents and visitors exercise caution if they choose to visit bars, restaurants, music venues and other public spaces.