STORY: Call it a sign of the times.

In Japan, adult diapers are starting to outsell those for babies.

That as birthrates there plummet and society ages.

Around 29% of the country's population is now over 65 - and that percentage is only set to grow.

Meanwhile, the number of babies born in the country fell for an eighth year in 2023.

At diaper maker Daio Paper, near Mount Fuji, factory manager Naoto Sugaya says the trend is clear:

"The number of diapers we're producing is increasing year by year thanks to the growing market for adult diapers in Japan. We're also producing a wide variety of diapers on account of the growing number of customers."

Over the five years to 2027, Japan's adult diaper market is forecast to grow 16% to over $600 million.

Meanwhile, sales of baby diapers are set to shrink 8%, to around $530 million.

One big maker - Oji Holdings - has already said it will stop selling baby diapers altogether.

At Daio Paper they've got no plans to stop making products for kids, but they're no longer the priority.

Marketing manager Kenji Nakata says the firm is shifting its resources to focus on the adult market.

They're also working to develop diapers that are discreet, and can be worn without embarrassment.

With countries around the world facing aging populations, Japan may not be the last to see diapers find new customers.