For Tosa, it may be tough hill to climb

London was the original plan. A pancake course that she knows well. A challenging field, led by Paula and Deena and a few other first-name stars. Big Ben for a backdrop. But then, Reiko Tosa began thinking about hills and history and changed her mind.

''No Japanese woman has won Boston," says the 29-year-old Tosa, who'll be favored to do just that in Monday's 110th running of the world's most legendary footrace. ''It is a chance to write history."

Tosa won a silver medal at the 2001 world championships in Edmonton. She finished fifth on the ancient course at the Athens Olympics. She has won at Nagoya, been second at Tokyo, fourth in London. ''Ms. Consistency" is her nickname, homage to her habit of finishing in the top five almost any time she takes the line.

What Tosa lacks, though, is a W from one of the world's Big 5. If she prevails here, she gets her own chapter in Japan's marathon annals. ''It would be the peak of my career," Tosa says through interpreter Nobby Hashizume. ''I would like my name engraved on that plate."

For the last seven years, Tosa has been a talented, if often overlooked, face on the planet's deepest hardtop team. Catherine Ndereba and her Kenyan teammates may have the reputation, but once a quadrennium, when everyone tunes in, it's the Japanese who are standing atop Olympus, watching the Rising Sun going up the flagpole. Naoko Takahashi in Sydney, Mizuki Noguchi in Athens. Who's betting against them in Beijing?

What makes the country's top women so formidable is the relentless push from below. Last year, 10 Japanese runners ranked among the world's top 25 marathoners and all of them were faster than the second American. Because they compete abroad infrequently, though, few of them are household names. Mari Ozaki? Megumi Oshima? Ryoko Eda?

Tosa, who bypassed marathoning last year to get married and focus on shorter distances (she anchored Japan's victory at the Yokohama Ekiden relay), was off the lists and off the international radar. With next year's world championships in Osaka coming up and the Olympics in 2008, she wanted to get back in the game.

London, where Tosa set her personal best (2:22:46) four years ago, was tempting, but Boston was irresistible. ''It is a very historic race," she says. ''I want to run it because of that." As far as her homeland is concerned, Boston is The Race and has been for more than half a century.

Japanese men have won here eight times, most notably Toshihiko Seko, who prevailed in 1981 (overtaking Bill Rodgers and Craig Virgin) and again in 1987. All of them are considered members of an exclusive club. ''Keizo Yamada [1953] won here more than 50 years ago," observes Hideo Suzuki, who coaches Tosa. ''Everywhere he goes to races in Japan, people still introduce him as the winner of the Boston Marathon. That is how much value the name carries."

Though they've frequently finished in the top 10 here (Mina Ogawa was eighth last year), no Japanese woman (except for Miki Gorman, who was a US citizen when she won in 1974 and 1977) has come close to winning. Yoshiko Yamamoto, the 1992 runner-up, was nearly three minutes behind Olga Markova. But this could be Tosa's time.

Ndereba, the four-time champion, is absent this year. Ethiopia's Derartu Tulu and Elfenesh Alemu, who would have packed a lethal 1-2 punch here, were late withdrawals. ''Lucky," Tosa says she feels. Though Tosa has the field's best time by 10 seconds, it won't be a walkover.

On her heels will be Jelena Prokopcuka, the Latvian speedster who won at Osaka and New York last year, outkicking Kenya's Susan Chepkemei in a sprint through Central Park. For added company, there's Lithuania's Zivile Balciunaite, the Tokyo runner-up, Ethiopia's Kutre Dulecha, the Amsterdam champ, Kenya's Rita Jeptoo, who was seventh at the world championships, plus Italy's Bruna Genovese and Serbia's Olivera Jevtic, the third-place finishers here in 2005 and 2004.

Tosa, though, is primed for a major effort. She has been training with her clubmates at altitude in China, where she prepared for her Olympic bid two summers ago. What she hasn't done much of, though, is specific hill work to simulate what Tosa calls ''the undulations" of Boston. If she had, jests Suzuki, ''she would probably be in the hospital."

What Tosa was preparing for was London's flat streets, until the idea of Boston beckoned. So five weeks ago, a call was made to Boston to see if a starting number might still be available. There was, and it turned out to be 1.

Tosa has studied up on the lore, on Heartbreak Hill and the rest of it. ''I have read the story of the Boston Marathon as well as the story of the city of Boston," she says. And once she arrived here this week, Tosa was informed of an effective shortcut to the finish line invented by a certain Ms. Ruiz. ''Wow, that's good," she says, giggling.

Too good to be true, or legal. If Tosa wants to make history here Monday, she'll have to be in it for the long haul and she'll have to beat several women who've placed in the top four here before and who know all the undulations by heart. No doubt, Tosa has the pedigree to be the first woman down Boylston Street.

She also has the expectation -- and the pressure -- to claim a laurel wreath that none of her countrywomen has been able to grasp. ''I'm trying not to think about it," Tosa says, laughing. ''Thanks for reminding me."