Backstage at a noh theater in downtown Tokyo, the play was about to begin.

One performer removed a mask from its box and placed it with infinite care on the face of the principal, who was engulfed in a costume of the stiffest brocade and staring straight ahead. Neither spoke, for they were in the kagami no ma (mirror room), the inner sanctum of a noh theater where humans and gods are believed to commune. The mood was ethereal and meditative -- which is expected in any noh space.

What's unusual, though, is that the two people were women -- Noriko Tomiyama and, in the mask, Yasuko Ueno. As such, they were a relatively rare sight in an artistic world dominated by men. Dominated, many would add, with an iron fist.

Once barred completely from noh, in the early 20th-century women were permitted to practice it as a hobby. Then, just after World War II, the most serious students among them were allowed to apply for professional status.

Today, there are some 250 female noh professionals nationwide. And though that comprises only a sixth of the total of 1,540, women now feel they have the numbers to speak out against practices in the male-dominated noh world that they consider unfair.

"We've been granted entry, but that doesn't mean we're allowed to do just anything," said Tomiyama, 77, who has devoted almost six decades of her life to noh, and is a member of the Komparu school. Of noh's five main schools for principals, this one, insiders said, is the most receptive to females.

Despite the progress they've made, women complain that gender-related hang-ups continue to prevent them from achieving full recognition. At the root of the problem appears to be the centuries-old concept of kegare (defilement). This holds that women are rendered unclean by the bleeding associated with menstruation and childbirth. With noh's Shinto-based passion for physical and spiritual purity, this presents a major stumbling block for women -- just as it does in sumo, where they are prohibited from touching the wrestling platform.

Said Tomiyama: "Everybody knows that if a man is available, the woman's only in the way -- even if she's a professional. No matter how lacking in talent a man may be, he's still considered better than any woman."

In this closed noh world, though, alongside such outright discrimination, taboos detrimental to women abound as well.

Michiko Kageyama, 55, a veteran actress of the Hosho school of noh, complained of being forbidden to touch a bell that serves as a central prop in the play "Dojo-ji" -- because she is a woman.

And then there is 79-year-old Reiko Adachi of the Kanze school, who describes establishments that would not allow women to touch or wear certain noh costumes -- so, effectively, preventing them from performing.

Even more important in that regard, the performers pointed out that until recently noh schools accepted only male applicants as uchideshi ("inside students"), year-round apprentices who receive essential basic training.

Komparu actress Tomiyama, for her part, seemed most insulted by the barring of women from okina, a ritual part of noh conducted as a prayer for peace and longevity. It is performed by men, and women are expected to keep their distance; some describe being banned from even helping with minor backstage chores when okina is under way.

"We're not saying we absolutely must perform okina," said Tomiyama. "But blocking us from the dressing room? Because we're impure? Now, that's a bit much."

Not surprisingly, male members of the noh elite downplay such charges. An official at the Association for Japanese Noh Plays, a prominent regulatory organization, said he did not believe the association consciously prevents women's involvement in okina. He added that the female membership in its ranks proved gender discrimination doesn't exist.

Nonetheless, female students of the Japanese theater could be excused for gazing back wistfully to Japan's middle ages, just before 14th-century playwright-performers Kan'ami and his son Zeami wove together elements of existing entertainment to create noh -- and before the highbrow artistic establishment told women that their services were no longer needed.

For example, women's historian Haruko Wakita at the University of Shiga Prefecture points to Hyakuman, a female performer who probably lived during the late Kamakura Period (1192-1333) and was famous for her kusemai, a dance with Buddhist and Shinto themes.

According to the scholar, Kan'ami learned the kusemai from a Hyakuman devotee, also a woman, and made the dance an integral component of his noh. Indeed, his son Zeami made sure to praise Hyakuman in his writings.

Alas, that early golden age of inclusion was destined to come to an end.

Mizue Mori, a university lecturer on Japanese religion and longtime amateur noh actress, explained that during the Edo Period (1603-1867), women performers gradually faded into obscurity as the political elite of the Tokugawa Shogunate tightened men's control over the ie (households) into which all of society, the noh theater included, was ordered.

However, women's exclusion from the stage didn't stop dramatists from creating some of the most important plays in the repertoire centered around female characters.

One form of noh theater, called Kazuramono -- "wig plays," from the hairpieces worn by performers -- focuses on female protagonists, and is said by male and female experts alike to be the most compelling variety of noh.

"Clearly, the artistic high point of a noh performance is the play about woman [sic]," performer Kunio Komparu, a male descendent of noh's founding fathers, wrote in his English-language book "The Noh Theater." (In Edo times, a customary noh program consisted of five plays from as many categories. Today, the maximum is usually three, plus a performance of kyogen, a brief and usually comic skit.)

In fact, the relationship between male and female facets of the human character is a key element of the noh mystique. Performers switch freely between gender, for instance, to play a woman in the first act and transform into a man later on -- or, like the woman's ghost dressed in her husband's clothes in the play "Izutsu (The Well Curb)," a character suggesting androgyny.

All of which begs the question: If the portrayal of gender is so fluid in noh, shouldn't women have an advantage over men performing female roles?

Experts on both side of the gender divide explain that it's not as simple as that.

First, there is the audience to consider. Having grown accustomed to men performing principal roles accompanied by usually all-male choruses called jiutai, there are Japanese patrons who find a woman principal as odd as, say, soprano Beverly Sills standing in for Placido Domingo's Otello.

Offering his own opinion, Agency for Cultural Affairs official Hirotsugu Saito said, "Noh is a musical form, so reconciling differences in voice timbre is an important artistic consideration."

Women performers readily acknowledge that no matter how much adjusting they try to do, there are some parts for which they are just not suitable, such as tough-guy roles that require them to appear without a mask or deliver lines with the kind of gruffness that only an old man can muster.

"Some things just don't sound right in a woman's voice. But let's not forget that there are male performers who look funny as women, too! It's the same issue the other way around," said actress Kageyama.

In the end, women performers' only solution is . . . to simply nurture more women performers.

Tomiyama is doing just that, passing on her experience to several female students, including four professionals and one young girl who has hinted that she wants to make noh her career.

At the prestigious Tokyo National University of Fine Arts and Music almost half of the 29 students of noh this year are women.

Still, the opportunities for women principals to be accompanied by all-female choruses are scarce -- even in Tomiyama's school of Komparu. And so women must continue, for now, to accommodate male voices.

"Until we have women in lead roles, filling the chorus, assisting on stage or with the wardrobe," said Tomiyama, "we won't have women's noh."