A major Japanese hygiene product maker began selling the world's first "horizontally" recycled disposable diapers on Saturday as the country's aging society undergoes a shift in demand from children's diapers to those for older adults.

The diapers, manufactured by Unicharm Corp., were created under "horizontal recycling," which refers to worn things being reproduced into their original form. Retailer Aeon Kyushu Co will eventually sell them in 68 stores. 

According to the Mainichi Shimbun newspaper, Unicharm, based in the southwestern prefecture of Kagoshima, worked with local governments to sell adult and baby diapers this month in shopping centers on Kyushu, one of the country's four main islands. 

They are referred to as "horizontal" products because the replicated items are identical to the ones they were recycled from instead of being transformed into new products. 

Unicharm said it had used ozone-based sterilization, bleaching, and deodorizing technologies to ensure the recycled diapers were odor- and bacteria-free.

Tsutomu Kido, a senior executive officer at Unicharm, said they have received expert support for hygiene. 

Kagoshima's hospitals and nursing homes have used recycled diapers since they were created in 2022. 

In a statement, Unicharm said children's sizes are among those already available for purchase and are slightly more expensive than standard disposable diapers. It added that the customers who have used these products said they were comfortable and felt no difference from regular diapers. 

Japan's demographic shifts have resulted in a decline in the market for children's diapers, but sales of adult diapers are expected to increase.

Last month, Oji Holdings, a manufacturer of paper products, announced that it would begin producing more sanitary items for the elderly and stop making children's diapers later this year due to a significant drop in demand.