OSAKA -- Less than six months remain until the curtains open on the 2025 Osaka-Kansai World Expo. Ticket sales have started at convenience stores and travel agencies across Japan, and reservations have opened for some opening day visits. The exteriors of domestic pavilions have been completed, and work is now underway on the interiors or preparations for the exhibits at some pavilions.

The Mainichi Shimbun is getting a preview of some of the highlights under wraps, including an AI-updated throwback to the "human washing machine" showcased at the previous Osaka expo in 1970. Aside from updated technologies, the version of the machine made for the new era 55 years later will also be packed with ideas from two lead designers of the original.

The late Toshio Iue, founder of Sanyo Electric Co., suggested, "Machines to wash clothing sold well, then shall we make a machine to wash the person?" Under Iue's auspices, the company developed just such a machine for the 1970 expo. Its large, egg-shaped bathing capsule filled with hot water, and ultrasonic waves from bursting bubbles cleaned the body of the bather.

The machine was dubbed the "ultrasonic bath" and shown at Sanyo's expo building, where its unusual design and cutting-edge idea caught a lot of attention. In an age when not every household had a bath, a crowd gathered to step into the skeletal capsule tub for test baths.

Eiji Yamaya, an 84-year-old resident of Kyoto's Kita Ward, oversaw the original machine's development as a Sanyo engineer, and had to order parts and manage the process himself because the company was too busy with its main business to provide workers for the project.

Yamaya struggled to find ways to continue the work, recalling, "If it used the same conventional technology, it would embarrass my superiors and the company." A hint came when he found a reference to the fact that small underwater air bubbles release ultrasonic waves when they burst. For the original, there were no tools or specializing organizations to properly measure the impact strength of the ultrasonic waves. The exhibit was decided upon in haste, he said.

Yamaya recalled his complex feelings at the time, saying, "We aimed for small bubbles, which we thought would remove more dirt, but it was technically difficult. Due in part to the company's policy of emphasizing appearance, we ended up with large bubbles in the exhibit. As an engineer, I didn't want to do that."

The machine's designer was Manatsu Ueda, a 90-year-old resident of Toyonaka, Osaka Prefecture. "The egg shape was chosen because it is the most stable form and for the gentle impression given by its curves. Since it was expected to garner attention at the expo, two units were prepared just in case," Ueda recalled.

At the upcoming expo's health care pavilion, which will include exhibits by the municipal and prefectural Osaka governments and others, Osaka-based Science Co. is preparing the successor to the last expo's machine, dubbed the "future human washing machine." The company has been developing showerheads and bathtubs that utilize technology that removes dirt with microscopic bubbles.

The human washing machine of the future doesn't just wash the body. Sensors scanning the person's back measure their levels of stress and fatigue, and in response, the device outputs imagery in pace with their state of body and mind to create a relaxing space for them. There are also plans to enlist regular expo-goers to try out the device.

Even after hitting retirement age following changing jobs from Sanyo, Yamaya couldn't shake the desire to improve and commercialize the product, and has since continued to refine the plans.

Opportunity struck in 2021. When he saw a TV commercial for a showerhead by Science, the thought immediately hit him that it could be used to update the human washing machine he had created. He called the company.

At the time, Science's chairperson Yasuaki Aoyama, 64, had just made a pact with Ueda to meet and get words of advice on fashioning the updated device. With this sort of coincidence in place, the company set about development, propelled by help from Yamaya and Ueda.

Yamaya told the Mainichi, "The human washing machine in my time only washed the body, but this time, an advanced function that uses sensors to determine the body's condition has been added. I want the world to see Japan's technological capabilities."

Other state-of-the-art technologies will be showcased at the Osaka health care pavilion.

Rohto Pharmaceutical Co. will host an exhibit related to eye care, one of its mainstay business fields. Visitors will be able to photograph their faces to get an "eye-sessment" of their peepers' condition.

Meanwhile, a group made up of Osaka University and companies is planning an exhibit related to 3D-printed "cultivated meat" made from the cultured muscle and fat cells of Japanese cattle.

(Japanese original by Tatsu Shingu, Osaka City News Department)