What's green, fuzzy and has a starring role in Japan's national anthem?

And no, it's not Kermit the Frog, who wasn't around when the lyrics for "Kimigayo" are thought to have been penned, sometime in the 9th century.

The answer is moss — the soft green plant that grows on forest floors and in other damp and shady locales. The lyrics of Japan's national song express the desire that the Emperor's reign continue "until the pebbles grow into boulders lush with moss."

Japan's stones evidently don't roll.

One would think that a mention in the national anthem would guarantee the little plant some cultural cachet in Japan. Unfortunately, no, says Norihiro Kotake.

"Everyone has heard of moss, but they don't really understand how important it can be," says the man who three years ago helped launch a company called Kokemori, which is now trying to take moss to the masses. Kokemori sells various moss-keeping kits and even wall-mounted frames full of live moss that can be displayed in the home or office.

"Moss is not only a lot of fun, but it has some very important benefits," Kotake explained. "For starters, moss can help maintain a consistent level of humidity in a room."

Moss, it turns out, can not only absorb moisture, but emit it, too.

"When the humidity falls below about 12 grams/cu. meter, moss will let out moisture," Kotake said. "And when the humidity goes above about 17 grams/cu. meter, moss will absorb moisture."

In common parlance, that means if you have a bed of healthy moss in your room, you will continue to enjoy a comfortable relative humidity of between 40 percent and 60 percent.

"We also know that influenza is most likely to spread when the humidity drops below 10 grams/cu. meter, so moss actually acts to stop that," Kotake said.

In addition, moss acts as an air purifier. Instead of absorbing water and nutrients from the ground through a system of roots, moss sucks them in from the air around it.

"That means it actually collects unwanted particles from the air and stores them inside itself," Kotake said.

Restaurants and clubs are among Kokemori's key clients. "If you install a bed of moss in a smoking room, for example, it will actually absorb the smoke," he said.

So how do you go about "installing" moss?

Readers who enjoyed childhoods in the great outdoors might recall attempts to transplant moss from a forest floor to an ice-cream container or some such vessel. It's unlikely such attempts ended well. The tricky part is establishing a ground for the moss that can be kept consistently moistened with fresh water.

Kokemori has created two contraptions that achieve this. One is for flat, horizontal surfaces, and the other is for walls.

"The wall-mounted one is special," Kotake said. "It took a long time to make that work."

While not wanting to divulge too many details, he explained that the technique involves the use of dried sphagnum, which is a type of moss. Dried sphagnum is so absorbent that it is often used in flower arrangement in order to keep the stems of cut flowers hydrated.

The dried sphagnum is packed into a rectangular, net-covered box resembling a picture frame. Then, a small, perforated hose is laid across the top to deliver water that trickles down through the sphagnum. A pump delivers the water that collects in a tray below back up to the top where it begins its cycle again.

Once this framework is in place, clumps of live moss can be tucked into the dried moss and made to grow.

Kotake and his staff have managed to turn these contraptions into what might be called "moss art." By combining different colored moss (there are thought to be over 2,000 different varieties of moss in Japan), it is possible to make pictures.

"In one European restaurant we made a map of the Mediterranean in moss," Kotake said.

And how much do such masterpieces cost?

The largest, which are more than a meter in length, can sell for over ¥1 million, but small kits for household use start from around ¥30,000. The company also conducts maintenance as it is occasionally necessary to change the water and add new moss.

And it seems Kotake and his Kokemori partners are not the only ones singing the praises of moss. Bruce McCune, a professor of botany and plant pathology at Oregon State University, held a student workshop on the subject back in 2000. "Our goal is to enhance public awareness of the effects and benefits of mosses in our everyday environment," McCune's students proclaim on their website.

Still, while those students investigated the use of moss on sidewalks, rooftops and gardens, they didn't delve into its potential applications inside the home. For that, it seems, you have to be in Japan — the only country in the world where, as far as this writer can ascertain, moss is celebrated in the national song.

Readers interested in learning more about growing moss should see the Kokemori website: ameblo.jp/kokemori/