It's about time the conservative sumo wrestling world and Japan get used to a dose of diversity.

Yokozuna Asashoryu

In keeping with his bad-boy image, 330-pound Asashoryu, one of sumo wrestling's two yokozuna (highest ranked) grand champions, recently ended up in a drunken scuffle outside a Tokyo bar, breaking the nose of one of his drinking partners. Occurring in the middle of the year's first two-week tournament, the brawl outraged sumo wrestling's tradition-drenched governing council, which has been known to rebuke wrestlers for looking at their opponents in the wrong way.

Had the Mongolian Asashoryu been a run-of-the-mill slinger he may have been kicked out of the sport altogether, particularly as the brawl was the latest in a string of incidents involving the errant athlete that have shocked sumo aficionados. His list of misdemeanors includes being caught playing in a charity soccer match in his native Mongolia when he was supposed to be recovering from a back injury; having the audacity to play a round of golf two days before a tournament; wearing flip-flops and a Hawaiian shirt on vacation; twirling tassels on the traditional sumo belt that wrestlers wear to bouts; and throwing purifying salt into the ring with his left rather than his right. All are deemed unfitting behavior for a supposed-to-be stoic yokozuna.

But average Asashoryu is not. He won the latest tournament with a bruised fist and a hangover, adding to a list of victories that has made him one of sumo's most successful wrestlers. He has pulled in fans that love him and love to hate him, driving a renaissance in the centuries-old sport. It's a long way from the showbiz of WrestleMania but it enthralls millions of Japanese. Another mark against Asashoryu, and the one thing beyond the impish wrestlers control, is that he's a foreigner. And he's not the only one. Japan's other grand champion, Hakuho, is also Mongolian (he was caught playing golf with Asashoryu). A notch down at Ozeki rank is fellow countryman Harumafuji and Bulgarian Kotooshu.

Sumo's ruling body is so worried by the influx of alien wrestlers that it has put a cap on non-Japanese participants, limiting each stable to one wrestler and robbing spectators of the opportunity to see the very best on offer. Sumo may get the homegrown champion it sorely wants, but at the risk of killing the sport altogether. Japan, like sumo, is closed, preferring to persevere through depopulation and economic stagnation rather than open its borders to the stimulus offered by opportunity-hungry foreigners.

What they choose to ignore is that Japan is running out of money, people and ideas. Its debt is already nearly twice GDP. Rating agency S&P on Jan. 26 said it may lower the nation's sovereign debt rating unless Asia's biggest economy can get a grip on its deficit. By 2030 there will be 10 million fewer Japanese than there are now, its workforce losing half a million tax-paying wage earners a year as its baby boomers head into retirement. Yet lawmakers struggling to find a solution to halt the slow loss of economic vitality refuse to suggest one obvious fix: immigration. Like sumo's aloof overlords, they seem to prefer irrelevance to diversity.

Should it swing open its doors to foreigners, Japan, like European nations such as the U.K. and France, will have to get used to a lot of unfamiliar behavior and social strife. The payoff is worth it. Japan will never resemble an American melting pot, but as Asashoryu and his fellow foreign wrestlers have demonstrated, it's worth putting up with a few antics for a healthy dose of diversity.