Users lie down in the pod, close the lid and get cleaned like clothes in a washing machine -- but without the spin -- while music plays.

A prototype of the device, called the human washer of the future, attracted long queues at the six-month Expo that wrapped up in Osaka in October after welcoming over 27 million people.

Made by Japanese firm Science, the device is an update of a product displayed the last time Osaka hosted the event, in 1970.

"Our (company) president was inspired by that as a 10-year-old boy at the time," Science spokeswoman Sachiko Maekura told AFP.

The machine "not only washes your body but also your soul," she added, while also monitoring users' heartbeats and other vital signs.

After a US resort company contacted Science to see if the prototype would be commercialised, the firm decided to produce it for real.

A hotel in Osaka bought the first machine and is preparing to offer the service to hotel guests, the spokeswoman said.

Other customers include Yamada Denki, a major consumer electronics retail chain in Japan, which hopes the machine will draw people to visit its outlets, she said.

"Because part of the appeal of this machine is rarity, we plan to produce only about 50 units," Maekura said.

Local media reported that the retail price will be 60 million yen ($385,000).