Japan's cash registers are being kept busy with sales of the latest wonder product - a spray-on silk stocking that could mean women will never again have to worry about runs in their stockings.

"This product is really easy to use; it dries very quickly - you just have to spread it over your skin," explained Hanae Seki, the cosmetics manager at the Sony Plaza store in Tokyo's Ginza district.

The stocking is simply sprayed onto the leg

"It's perfect for Japan's summer season, when traditional stockings are too hot. We're selling several hundred bottles a month - people are coming from all over Japan to buy them."

The product is called the Air-Stocking - a fine, silk aerosol spray.

Available in terracotta, natural or bronze colours, they cost about $12. You get about 20 pairs of stockings in one can.

The inventor, Yoshiumi Hamada, explains his inspiration from his cramped office above a women's swimwear shop.

"The idea came to me about three years ago, in the middle of summer. One of the women who works here said she didn't want to wear stockings because it was too hot and she said she'd like to wear sandals to show off her pedicure," Mr Hamada said.

"The challenge was to create something that made legs look beautiful but wouldn't hide the pedicure," he said.

But what are the stockings actually like?

Judging myself unqualified in such matters, I asked Tamami Shimizhuishi, a local student, to road test the tights in a can.

The air-stocking is also waterproof, so when the summer ends, they can still be worn safely in monsoon season

I asked her what it felt like as the spray went on.

"It's really cold, so, you know, in the morning when I feel really hot, it might be really comfortable," she said.

And of course you have to be very careful about your clothes as well, because it does come with a warning that it can mark clothes.

"I don't think I want to do this kind of process in the morning. In the morning five minutes is pretty precious!," Ms Shimizhuishi said.

But the final result meets with a reserved approval from Tamami and her friends.

It does almost look like she is wearing regular silk stockings. And with a lot of soap, and a bit of scrubbing, they can be washed off in the shower.

Pressure to be smart

Fashion critic Yuko Ishihara is certainly a fan. She says the stockings are the best thing since the invention of the ever-lasting lipstick.

"The pressure is on women workers to wear stockings, especially in the more conservative Japanese conglomerates," she said.

"But more casual fashions are gaining ground here. That's why products like this are doing so well.

"Japanese women are getting more adventurous. These days they like to wear tights with flowers on, or even racy fish-net stockings," she added.

As the temperature rises, Japan's stores are struggling to keep up with the demand.