There is nothing much more Japanese than onsen and sento: hot springs and communal public baths. Now Gokurakuyu, Japan's largest spa operator, plans to take them to China – tackling poor hygiene, a booming property market and misgivings about public nudity along the way.

Along with its partners, an affiliate of China's Citic Group and Japanese investment company MBK, Gokurakuyu aims to open its first Chinese spa by March next year. In five years it wants to have 100 of various sizes. That is more than it has in Japan.

The boldness of Gokurakuyu's move highlights a new trend: while Japan's manufacturers have long made and sold their goods in China, Japan's insular service sector is finally making a big move on to the mainland.

Whereas in 2005, Japan made a net $19bn of direct investments in non-manufacturing businesses overseas, in 2009 the figure had reached $42bn, according to data from the Japan External Trade Organisation. Much of that went to China, although the use of holding companies in Hong Kong and the Cayman Islands makes measurement tricky.

In retail, Yamada Denki, one of Japan's largest electrical retailers, and Asahi, its largest bicycle shop, plan to open their first stores in China this year.

The parcel delivery vans of Yamato Holdings, ubiquitous in Japan, may soon appear in China after the company opened a logistics operation in Shanghai this year. In 2009, Yamato earned more than 98 per cent of its revenue in Japan. China is one of its first big steps abroad.

There are many more, from Secom, the home security company that has been in China for some years, to Oriental Land, the operator of Tokyo Disney Resort, which has said it may work on development of a new Disney resort in Shanghai.

All of these companies have ample motivation to move into China. Population decline and economic stagnation make it hard to expect growth at home, while the strength of the yen means it is an attractive time to invest abroad. Japan's service companies hope that cultural barriers will be relatively low and growth rapid in China.

But success will require adaptation to local conditions as Gokurakuyu has learnt. “The Gokurakuyu format in Japan will be the base,” says Shunji Matsumoto, director of Gokurakuyu's expansion overseas, but for China each spa will have to be three or even five times bigger. Whereas Japanese customers are used to the idea of lots of bodies sharing a fairly small bath, in China, Mr Matsumoto says, “We're thinking that unless there is more space per person, then customers won't really be able to relax.”

Another difference, is that a Japanese onsen is purely a place to relax, but Chinese spas tend to include private rooms for doing business. Finally, and especially in areas of China not used to communal bathing, Gokurakuyu expects to include an area for customers who want to wear swimming costumes.

Gokurakuyu's selling point will be its Japanese standard of service and hospitality. That means not just polite and friendly staff, but rapid repairs to things that go wrong, and close attention to detail.

“Hygiene is an important part of our service,” Mr Matsumoto says. Quite often, he says, a Chinese spa will have the necessary hygiene equipment but will not run it to save money, or it will install equipment that cannot handle the necessary volume. To meet its service standards, Gokurakuyu plans to hire Chinese staff who have lived in Japan.

One problem Gokurakuyu has is China's booming property market. The government owns many possible sites and private landowners are reluctant to build one-storey spas when they could construct something bigger. “It's a real struggle to find locations,” Mr Matsumoto says.

It is possible to put a spa into a taller building, but a labyrinth of piping takes up more than a metre of space under the floor, and it is heavy. That makes Gokurakuyu nervous about using any structure not designed for the purpose.

Citic's connections are helping to find sites and Gokurakuyu aims to start off in big coastal cities. It will experiment with various formats before pushing ahead with expansion and is counting on franchises to get to 100 spas quickly.

Whether Chinese consumers will take to steaming together in an elegant Japanese hot tub remains to be seen. But for Japan's service companies a move into China looks like their best hope to achieve profits and relevance.