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.