You are the prime minister of Japan, you say? How nice for you, but you still can't join this club. A movie star? How tacky. A billionaire businessman? Forget it. Money can't buy you blood -- not the right blood, anyway.

The right bloodlines are everything at the Kasumi Kaikan, Japan's most exclusive social club. There is no direct translation of the club's Japanese name, but "Peers Club" or "Aristocracy Club" is probably closest: All 950 members are men, the eldest sons and grandsons of Japan's old nobility.

If World War II hadn't turned out the way it did, these men would have inherited the titles of dukes, counts and barons. Many would be living in grand homes amid opulence and antiquity. But the Americans ended all that, stripping the nobility of its land, wealth and status. When the Americans occupied Japan, the emperor renounced his divinity and the aristocrats went looking for paying jobs.

"After the war," says Nagahide Kuroda, whose father was chamberlain to Emperor Hirohito, "my mother had to cook for the first time."

This club is the nobles' revenge.

It is a fantastic spread that occupies the entire 34th floor of a skyscraper overlooking Tokyo's government center. Here, a duke can still feel like a duke -- even if he now sells software for a living. He can smoke a good cigar and sip 12-year-old single-malt whiskey with other men of noble bearing -- sometimes the emperor himself drops by. He can shoot pool amid priceless treasures of Old Japan. Virtually unknown to those outside the upper crust, the club has had a profound effect on the preservation of Japanese tradition and artifacts. Many club members view themselves as keepers of Japanese culture. For them the club is not about looking backward and lamenting a soft life lost: Their mission is to preserve for future generations such ancient arts as waka, traditional 31-syllable poetry, and emon, imperial court dressing.

When Emperor Akihito formally ascended to the throne in 1990, a team of 70 people from the Kasumi Kaikan was enlisted to dress him and other members of the royal family in the elaborate robes used in the ceremony. They did the same when Crown Prince Naruhito married Princess Masako in 1993.

"It is easy to pass on a painting or a kimono, but it is hard to pass on the process of making these things in the traditional way," says club member Tetsuo Ito, curator of the Suntory Museum of Art in Tokyo.

The club regularly offers classes in the traditional arts, including an incense-smelling course in which students sit around a long table and try to sniff out the difference among six basic types of incense.

Members of the Kasumi Kaikan have opened or donated items to more than 100 museums, filling them with priceless samurai swords, rare scrolls, hand-painted screens, pearl lacquer boxes and other heirlooms.

Of course, there are certain benefits to all this benevolence. Creating a nonprofit museum to house your priceless art objects is a nice tax shelter. It ensures the aging club members that their children won't have to sell these last vestiges of their prewar lives to pay Japan's terrifying inheritance tax, which claims up to 70 percent of inherited wealth.

But club members insist that the club, founded in the 19th century, is not about personal wealth. The club also funds social welfare projects, libraries and international student exchanges. Wives and daughters of members do much of the club's volunteer and cultural work, though as nonmembers they are not permitted at the bar or pool tables.

Many of those who love Japan are fearful that what sets it apart from the rest of the world -- its samurai legacies, kimonos, music, tea ceremonies -- is disappearing in a world where millions of people watch the same Hollywood movies and eat McDonald's burgers.

"If we were interested in money, we could sell just one piece of art and buy a gorgeous house," says club director Kuroda, an elegant, thin man who walks with perfect posture. "But then Japanese culture would deteriorate. It is our duty to keep it intact."

In this country where a golf club membership can cost half a million dollars and the cover charge at some nightclubs is $400, the annual dues at the Kasumi Kaikan are just $50, about the price of a haircut.

The low fee is the result of a shrewd real estate deal made long ago.

Shortly after World War II, a developer approached the club about building Japan's first skyscraper on the land where its old clubhouse had stood. Faced for the first time with financial troubles, the club members struck a deal: They allowed the developer to build the 35-story building, but they retained ownership of the land, two floors of the building to rent out themselves, and the 34th floor for their clubhouse.

The building today sits in the center of Kasumigaseki, Japan's government center and some of the most prime real estate in one of the world's most expensive cities.

Club members won't say how much rent they receive from the land or the two floors of office space. But they offer a sly hint: They pay more than $750,000 a year in tax on it.

A club genealogist is on hand in case there is any question about a potential member's lineage, and a committee investigates the character of those who want to join. Kuroda says members must take seriously their duty to pay respect to their ancestors and to be of "good reputation."

The men of the Kasumi Kaikan tread in quiet luxury. A thick carpet with the club's cherry blossom insignia warms the entrance, which is lined with old framed photos of aristocrats in their salad days. The various function rooms, studies, dining areas and game rooms can easily swallow 500 people and still leave the club with the quiet feel of a library. Members wear their cherry blossom lapel pins at all times -- red ones for those over 80 and gold ones for those who reach 90. Hiroshi Komatsu, who helps run the club, says members "never talk about their family history to one another. Everybody knows who they are."

And everybody knows the painful reverse Cinderella stories that brought them here.

Kuroda's family lost untold sums when an American bomb destroyed its ancestral collection of treasures. And when the rubble was cleared after the Japanese surrender, the Kuroda family's grand home -- and the luxurious way of life it had enjoyed for generations -- was swept away in the new meritocracy that emerged.

Akira Watanabe, 96, was well into his forties when his life dramatically shifted. "Nothing was left," he says; not his family compound, his horses, his gardens, his aviary. "Each child had had their own servant." Watanabe, a cheerful, energetic man who comes to the club nearly every day, says club members rarely tell their family stories. He says they all have come to accept their new status as men whose nobility stops at the clubhouse walls.

"It can't be helped," Watanabe adds with a wise smile. "We lost the war."

Special correspondent Shigehiko Togo contributed to this article.

CAPTION: Gyoun Sanjounishi, a master at kohdo -- the art of fragrance appreciation -- leads a class for women at the Kasumi Kaikan in Tokyo last month.

CAPTION: Joerg Tanger of Germany, a guest at the Kasumi Kaikan, in ceremonial attire. The club's members are among the few who remember the art of imperial dressing.