The Tosa (also called the Tosa Inu or Japanese Mastiff) is a breed of dog of Japanese origin that is considered rare. It was originally bred in Tosa (present day Kōchi) as a fighting dog and still is today.

This breed originated in the second half of the nineteenth century. The breed started from the native Shikoku-Inu, an indigenous dog weighing about 25 kilograms (45 pounds) and standing about 55 centimetres high, which closely resembles the European Spitz. These dogs were crossed with European dog breeds, such as the Old English Bulldog in 1872, Mastiff in 1874, St. Bernard, German Pointer in 1876, Great Dane in 1924, and the Bull Terrier. The aim was to breed a larger, more powerful dog. The heyday of Tosa breeding was between 1924 and 1933, when it was said that there were more than 5,000 Tosa breeders in Japan.

Ownership of Tosas is legally restricted in certain jurisdictions. In the United Kingdom and Republic of Ireland ownership is regulated under the Dangerous Dogs Act 1991, and in Trinidad & Tobago under the Dangerous Dogs Act 2000. A specific exemption of a British court is required to own and import Tosas legally in the UK.

The breed is illegal/banned in:

Australia, Cayman Islands, Cyprus, Denmark, Fiji, Hong Kong, Iceland, Israel, Malaysia, Malta, New Zealand, Norway, Singapore, Turkey, Tunisia and the United Kingdom.

More Info: en.wikipedia.org