Prime Minister Ishiba Shigeru attended the opening ceremony for the Osaka Expo on April 12 along with Emperor Naruhito and Empress Masako.

Ishiba also visited the Osaka Healthcare Pavilion that features a device that can predict a person's health condition 25 years from now.

The facility also has a state-of-the-art human washing machine.

Ishiba said he also saw a human washing machine at the 1970 World Exposition held in Osaka Prefecture.

The 68-year-old Japanese leader asked officials when the human washing machine will hit the market, saying he wondered the same thing 55 years ago.

The World Exposition will be held from April 13 to October 13 on a manmade island called Yumeshima in Osaka Bay.