All Kurobuta pork comes from Berkshire pigs. That does not mean that meat from all Berkshire pigs, though, qualifies as Kurobata grade.
Kurobuta Pork is darker than standard pork, with a richer taste, soft white fat, and good marbling throughout. It is never injected with brine water “seasoning”, as much pork is. It is very expensive.
The only real Kurobata Pork is from pigs raised in Japan, though producers in the UK, United States and Australia are claiming to produce it. There’s a complete breeding, feeding and management system that has to go with it. That is not to say the Berkshire pigs have to be born in Japan. The pigs can be brought in from places such as the United States, and then raised in Japan. The pigs, though, must be certified purebred, under Japanese Ministry of Agriculture, Fisheries and Food (MAFF) rules passed January 2000, if the meat is to be sold under the Kurobata classification.
In Japan, most Kurobata is produced in Kyushu.
Pork being sold as Kurobuta in the UK is being raised in Worcestershire by a Craig Walsh at Lucies Farm. The pigs there are fed beer and grain, and are allowed to go swimming (this is not part of the regime in Japan.)
Pork being sold as Kurobuta in the United States is raised by Snake River Farms and Eden Farms.
Berkshire pigs reputedly were given by the British goverment to the Kingdom of Ryukyu (now Okinawa, Japan) in the 1800s . From there some pigs were sent north to Kyushu.
Disregard stories associating the pork with Oliver Cromwell.
 We have not found any backing for this.
“Kurobuta” in Japanese means “black pig.” The pigs are covered in black hair.
Duffy, Nikki. Kurobata Pork. Manchester: The Guardian. 5 August 2006.
USDA Foreign Agricultural Service. Japan Market Development Reports Food Business Line – Periodic Press Translations. GAIN Report Number: JA7501. 19 January 2007.