Tokyo-X is a new Japanese

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

 breed of domestic pig

Domestic pig

The domestic pig is a domesticated animal that traces its ancestry to the wild boar, and is considered a subspecies of the wild boar or a distinct species in its own right. It is likely the wild boar was domesticated as early as 13,000 BC in the Tigris River basin...

, bred for high quality pork

Pork

Pork is the culinary name for meat from the domestic pig , which is eaten in many countries. It is one of the most commonly consumed meats worldwide, with evidence of pig husbandry dating back to 5000 BC....

 production. It is unusual for its marbled meat

Marbled meat

Marbled meat is meat, especially red meat, which contains various amounts of intramuscular fat, giving it an appearance similar to a marble pattern.- Selective breeding :Marbling can be influenced by selective breeding...

, seldom seen in pork.

The Tokyo-X breeding effort was begun in 1990 by the Tokyo Metropolitan Livestock Experiment Station, combining bloodlines from the Duroc

Duroc (pig)

Duroc pig is an older breed of American domestic pig that forms the basis for many mixed-breed commercial hogs. Duroc pigs are red, large-framed, medium length, and muscular, with partially drooping ears, and tend to be one of the most aggressive of all the swine breeds.-Origins:The breed...

 (USA), Berkshire

Berkshire (pig)

Berkshire pigs are a rare breed of pig originating from Berkshire in England.Herds of the breed are still maintained in England by the Rare Breeds Survival Trust at Aldenham Country Park, Hertfordshire, and by the South of England Rare Breeds Centre in Kent. The Berkshire is listed as 'vulnerable',...

 (UK), and Beijing Black

Beijing Black

The Beijing Black, also known as the Peking Black, is a breed of domestic pig from China. They are mostly black, but have some white markings. The breed was created in 1962 by cross-breeding a Berkshire with a common Chinese pig. Two other breeds, the Soviet White and the Yorkshire, were also...

 (China) breeds. Five generations of breeding and selection ended in 1997 when the breed went to market.

Tokyo-X was also featured on the Japanese television program Iron Chef

Iron Chef

is a Japanese television cooking show produced by Fuji Television. The series, which premiered on October 10, 1992, is a stylized cook-off featuring guest chefs challenging one of the show's resident "Iron Chefs" in a timed cooking battle built around a specific theme ingredient. The series ended...

, where the cooks had to use it as an ingredient in each of their dishes.