TOKYO: Japan's excruciating wait for a home grown yokozuna, or sumo grand champion, ended Wednesday when 30-year-old Kisenosato was promoted to the ancient sport's highest rank.

A first Emperor's Cup triumph at the weekend was deemed good enough for him to become the first Japan-born wrestler to reach the lofty perch since Wakanohana in 1998, although it took Kisenosato 73 tournaments to get there -- longer than anyone since 1926.

"I accept with all humility," the 178-kilogramme (392 pounds) Kisenosato told reporters at a formal ceremony after being approved by the Japan Sumo Association (JSA).

"I will devote myself to the role and try not to disgrace the title of yokozuna.

"I feel a sense of relief," added the native of Ibaraki prefecture, northeast of Tokyo, before posing for photos while holding up a giant sea bream -- a traditional symbol of celebration in Japan.

"I'm overwhelmed with gratitude for all the people who have helped me reach this point."

Historians claim sumo dates back more than two millennia but the roly-poly sport been plagued by a series of damaging scandals in recent years.

It had been without a Japanese yokozuna since Wakanohana's brother Takanohana retired in 2003 as local wrestlers have been unable to repel a flood of foreigners who have dominated since.

"I would like to celebrate the first yokozuna promotion in 17 years from the bottom of my heart," Japan's Deputy Chief Cabinet Secretary Koichi Hagiuda told a daily press briefing.

"Kisenosato indeed has the necessary dignity and skill to carve his name in history."

The overseas invasion began in earnest with Hawaiian behemoth Konishiki, who was nicknamed 'Dump Truck' and tipped the scales at a whopping 285 kilogrammes (628 pounds), and other hulking Pacific islanders in the 1990s.

Mongolian rise

But the subsequent rise of the Mongolians, led by the brilliant but temperamental Asashoryu and latterly Hakuho, who has racked up a record 37 Emperor's Cup victories since 2006, has tormented sumo traditionalists in the absence of a Japanese challenge.

Mongolia, which boasts its own ancient style of traditional wrestling, currently boasts three yokozuna, with Harumafuji having won eight titles and Kakuryu three.

Former ozeki (champion) Kotoshogiku last year ended a 10-year wait for a Japanese Emperor's Cup winner, briefly raising local hopes, but failed to build on that momentum, much to the JSA's chagrin.

Mongolia's stranglehold over the sport, which retains many Shinto religious overtones, has prompted hand-wringing in sumo's corridors of power, none more so than when Hakuho surpassed the legendary Taiho to win a record 33rd title two years ago.

Japanese sumo officials have been accused of being overly harsh on Mongolian wrestlers, with critics insisting they lack "dignity", but even defenders acknowledge that Asashoryu broke protocol with alarming regularity.

The firebrand grappler won 25 Emperor's Cups before retiring in 2010 after being accused of breaking a man's nose in a drunken brawl outside a Tokyo nightclub.

Previously he had infamously provoked a soapy bathtub brawl with a rival and was banned for forging a doctor's note for a back injury, only to be caught on camera playing football wearing a Wayne Rooney shirt.

Meanwhile, allegations of illegal betting and links with crime syndicates, drugs busts and the bullying death of a young wrestler have shaken the closeted world of sumo to its foundations in recent years.

-AFP