When Momoko Sasaki goes traveling, she literally "goes an extra mile" to enjoy perks that few of her peers have likely ever dreamed of.

Recently, when she went on a three-week trip to Hong Kong, she flew out of Tokyo's Narita airport the wrong way -- eastward to New York. Then she came all the way back to Narita before switching planes to fly on her westerly way to HK. But then, after touring Hong Kong, Macao and mainland China, Sasaki flew back to Narita -- before winging away to the Big Apple again en route to her final destination . . . of Narita.

A flight attendant? No. A tireless corporate executive? Not exactly. Then who is she?

The answer lies in a shiny black card Sasaki takes out from her purse -- her membership card for a major U.S. airline's frequent-flier mileage program. Not just any mileage card, of course, but the kind only those who clock 100,000 air miles or more a year are entitled to.

"This is the highest-grade card you can get, apart from the really exclusive 'invitation only' type issued by airlines," said Sasaki (not her real name), at a Tokyo cafe recently.

Though in job terms she is a freelance business consultant, the willowy 27-year-old is probably best described as a member of the swelling ranks of maira (miler), a term coined to describe people who travel the world for the sole purpose of racking up miles.

Their aim? To win, and maintain, elite-status membership with airlines so they are pampered with perks, from priority check-ins and use of airport executive lounges, to double mileage points and seat upgrades.

Koji Hoshino, a travel journalist who hosts a Web site on traveling tips, estimates the number of maira at "several thousand" -- and rising.

"Each airline is said to have tens of thousands of frequent-flier members with an elite status," Hoshino said. "Most of them are business people. But a tiny portion of them are travelers who go out of their way to maintain their status."

Elite-class requirement

Sasaki said she normally combines her vacations with mileage-munching flights. But other flight buffs choose not to waste time, repeatedly taking "mile-efficient" routes, such as from Japan to New York, with little rest in between. The even more time-pressed ones, meanwhile, tend to specialize in domestic travel, flying to and from Fukuoka and Tsushima, a Nagasaki Prefecture islet near the Korean Peninsula, 10 times a day just so they can clear the elite-class requirement of 50 flights per year.

Their logic goes like this. Once you become an elite member of a frequent-flier program, you get 30,000 miles accumulated on your account for a round trip between Japan and New York. The 30,000 miles can then, for instance, be traded for a business-class ticket between Japan and Shanghai -- which, bought from a discount travel agency, would cost around 150,000 yen.

Mile-collectors do heavy-duty math before buying their flights, dividing the discount ticket price by the number of mileage points they can get. That way, they can achieve the best "yen-per-mile," Hoshino says, adding that the average value of a mile for international flights is 2 yen.

Mileage-minded flight buffs may not be exclusive to Japan, but in Hoshino's view the idea of exhaustively investigating flight cost-efficiency fits the Japanese psyche well. A love of minutiae might explain why so many Japanese are hooked to this time-consuming game/hobby/I.Q. test.

"Going on a weeklong vacation just to unwind and do nothing doesn't quite fit the mentality of many Japanese," he said. "They would rather pursue efficiency, even in travel."

For maira these days, more accumulation opportunities pop up all the time as airlines expand their link-ups with hotels, car rental, restaurant and even credit-card companies.

Late-lamented Concorde

A few years ago, for example, writer Hoshino himself took one of the late-lamented supersonic Concorde flights from London to New York return -- an experience that would have cost 1.8 million yen if he bought a regular ticket. Instead, he splashed out 120,000 yen on magazines from a U.S. Internet shopping site that was offering points to be traded for a luxury hotel break, switched those points to scoop 120,000 miles with British Airways and -- ole! -- savored Concorde on the supercheap.

In 2000, though, 10 Latin American airlines came up with a six-month promotional deal that was the stuff of a maira's wildest dreams. Then, anyone who could take flights with all 10 carriers, stay at affiliated hotels for three nights or more and rent a car for five days or more was rewarded with no less than 1,000,000 air miles!

Hoshino says many Japanese rose to the challenge, and earned enough credits for 13 business-class round trips between Japan and Europe.

All good fun, you may think. But not anymore for most maira, as many airlines are getting wise to their artful schemes. Once they may have excitedly chatted to all and sundry and on the Internet about their "conquests" -- now, they will only exchange the choicest cost-saving and bonus-yielding tips with friends in their inner circle for fear of rule changes by airlines. "It has gone analog again," as one frequent flyer moaned.