There is a new fad in Japan - and it involves underwear.

Some Japanese men and women are rejecting modern undergarments for the traditional loincloth, or fundoshi, which is typically worn by sumo wrestlers.

A group of volunteers have been heading out in the cold in Tokyo, dressed in the latest fashion trend, to pick up litter on the streets.

They told Reuters that they want to inspire the public to keep the city garbage-free and to "loosen up" as well, by turning to the fundoshi.

The loincloth fell out of popularity after World War II, when Japanese men turned to briefs and boxers instead, said Reuters.

Before the trend hit the streets, it was usually worn only during traditional festivals and by sumo wrestlers.

Fans of the fundoshi say it helps improve blood circulation.

The volunteers were organised by an online Japanese company that makes and sells the fundoshi, called Fundoshibu.

On their website, the company said it wants to start a "revolution in the underwear and fashion industry" with their loincloth products.

This is not the first time that attempts have been made to bring back the loincloth to the mainstream in Japan.

Last year, modern interpretations of the traditional underwear hit lingerie stores, targetting women.