New hot spring spas are being developed in Japan, even in Tokyo and other cities. Tone Geo Tech, a company founded in the 1920s, has helped develop more than 1,800 hot springs in different parts of the country. It finds hot springs by examining aerial photographs, conducting geological surveys, and using a wide array of exploration equipment.

One of the company's managers, Watanabe Kenji, says there was a big drive to open up hot springs after the government began giving local development grants worth 100 million yen to communities all over the country, about 15 years ago. "More and more cities, towns and villages, even places thought to be without hot springs, have tried to develop their potential as spas, using the technical advances in our industry."

It takes at least a year and half to transform a hot spring into a useable spa. Japan is a country rich in hot springs — so rich that no matter where you dig, you are likely to hit one. But it is not easy to find one suitable in terms of temperature, volume and cost feasibility.

"It's still very difficult to predict what is under the ground. When we hit a good spring, clients are all smiles, and that makes me happy, too."

For centuries, people have been coming to Shuzenji's hot springs on the Izu Peninsula in Shizuoka Prefecture. A different type of spa, Shuzenji Sparacio, opened there in 1997. It is run by a practicing medical doctor, Seki Akira, who also has a clinic in the town of Shuzenji.

"I came here more than 20 years ago and haven't had to take a day off since. I'm convinced my good health comes from bathing in the hot springs. I believe they can be used to prevent illness, and that's why I opened this therapeutic spa."

Shuzenji Sparacio has nine different types of pools. There are, for example, a herb sauna and an outdoor pool where bathers walk through the water. Lots of people come, hoping to relax the mind and cure the body.

"We know that the carbonated gas emitted at hot springs improves blood circulation, but many of the other possible benefits have yet to be scientifically explained. The psychological release you can get at a hot spring is receiving plenty of attention these days. Since ancient times, the Japanese have known, somehow, that a hot spring provides therapeutic benefits. I want to offer a modern version of the therapy bath."