Dear Alice,

What the heck is with all the Darth Vader impersonators in Japan? You know who I mean: the middle-aged ladies who bike around with menacing-looking windshields attached to their heads. I steer clear because the shields completely obscure their faces and I can't tell if they see me. Plus, that blank visage is downright creepy. Don't these women know how weird they look?

Alan H., Tokyo

Dear Alan,

Those women are wearing the extreme version of what is called a san baizaa in Japanese, from the English words "sun visor." Although there are plenty of tamer sun visors for sale here, the type you're talking about has an extra-long brim made of tinted see-through plastic of the sort used in cheap sunglasses. The brim — which ranges from 15 to 16.5 cm on the models I investigated — can be raised and lowered. When it's down, it covers the face right down to the chin.

I doubt the ladies are out to conquer the galaxy; they're just trying to keep the sun off their faces. Advertising copy for the visors claims they cut exposure to harmful UV rays by 99 percent, greatly reducing the risk of sunburn and skin aging. The design originated in Japan, but all the visors I saw for sale — for as little as ¥680 — were made in China or Korea.

You're not the only one who finds the Vader-on-Wheels look threatening. I turned up dozens of blog entries by people with similar complaints. "I hate it when I pull up to a corner and there's a cyclist with a full-face visor," one driver griped. "It's impossible to tell if they see you. They really should raise the visors at intersections."

My friend Masato goes even further, arguing that full-face visors should bear disclaimers in large letters. "How about a sticker that reads 'chanto mae o miteimasu' ('I really am looking where I am going!')," he snarked. "Or maybe 'goto de wa arimasen' ('This is not a stick-up!')

If I may stray a teeny bit off topic, I'd like to share a word I kept tripping over while researching your question. When I asked my friend Nagako what it meant, she laughed. "Geez, Alice! You know all sorts of difficult words but you don't know suppori?" I took this to mean we all ought to have that word in our vocabulary, and so I introduce it here as a public service.

Let me start by explaining that virtually every reference I found to full-face sun visors included the phrase 'kao o suppori ubau.' My Kenkyusha dictionary says "suppori" is an adverb that means "clean, clear, entirely." So a ho-hum, work-a-day translation of the visor phrase might be "covers the entire face." But the Japanese is punchier, so you could probably get away with a more literal rendering such as "steals the face clean away."

You know how you learn a new word that you swear you've never heard before, and then it suddenly starts popping up everywhere? Not one day after Nagako laughed at me, I heard "suppori" in use. My hairdresser was showing me how to pry the inner cap out of a travel-size bottle of shampoo so I could refill it. "Hora," she said, "suppori akerareru yo! ('See? You can get it all the way open!')."

But getting back to business, I wondered if you were right about who's behind the masks. I called distributors looking for buyer demographics but the most forthcoming source turned out to be a retailer in Fukuchiyama, Kyoto Prefecture called Tanimura Fashion Variety Goods. The company has been in business for 147 years, sells widely via Internet and advertises itself as a "sun-visor specialist."

"Every once in a while I sell one to a man, but 99 percent of buyers are middle-aged women," proprietor Tetsuro Onishi told me. "I've sold a lot to ladies who walk for exercise, and to women who bike around on errands. Those visors are better than hats for biking because they provide more sun protection and don't blow off."

"But sales have definitely dropped since the peak two years ago," Onishi added. "Now we've got new visors that look more fashionable, and I get the feeling that more women are using hiyakedome (sunscreen) lotions instead of covering up."

A dermatologist I spoke to concurred. "Japanese women of all ages have a high consciousness of the risks of sun exposure, and many are now using sunscreen products as well as the traditional method of carrying a parasol," said Kazumoto Toyofuku, head of the Yamate Dermatology Clinic near Takadanobaba Station in Tokyo. "The concern is not so much skin cancer, which is very rare in Japan, but beauty. The general belief in Japan is that pale skin is more attractive, and women are very aware that UV rays cause discoloration as well as damage."

Japan probably has the most advanced sunscreen technology in the world, according to Toyofuku, who advises cosmetic companies in developing sunscreens. "We have a large market of motivated users, and companies are investing heavily in development. There are some very exciting things going on with waterproofing technology, for example, and I think it's likely that we'll soon have products that can actually repair cell damage caused by sun exposure."

Toyofuku tells his patients to use a sunscreen with a three-plus PA rating (PA +++), which is the Japanese measurement of protection against UVA rays, as well as a SPF (Sun Protection Factor) of 30 for everyday use and 50 for outdoor sports. SPF measures protection against UVB rays, which cause burning, but you also need protection against UVA rays that penetrate deeper and cause aging as well as tanning.

In addition to sunscreen, Toyofuku suggests using a parasol or a hat with a wide brim, noting that even a modest 7-cm brim cuts UV exposure by 60 percent. A full-face Vader visor would be even better, he acknowledged, because it would block out almost all UV rays. "But I would never push one on a patient," he said. "They just look too weird."