Maguro bōchō or Maguro kiri bōchō (マグロ切り包丁, lit. "tuna cutter") is an extremely long, highly specialized knife

Knife

A knife is a cutting tool with an exposed cutting edge or blade, hand-held or otherwise, with or without a handle. Knives were used at least two-and-a-half million years ago, as evidenced by the Oldowan tools...

 used in Japan

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...

 to fillet

Fillet (cut)

A fillet is a cut or slice of boneless meat or fish.- Meat :In the case of beef, in the USA, the term most often refers to beef tenderloin, especially filet mignon.- Chicken :...

 tuna

Tuna

Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...

 and other large fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

.

The maguro bōchō is a longer knife with a blade length of 40 cm (16 inches) to 150 cm (60 inches) in addition to a long handle. It can fillet a tuna in a single cut, although usually two people are needed to handle the knife and the tuna. The flexible blade is curved to the shape of the spine to minimize the amount of meat remaining on the tuna carcass

Carcass

Carcass may refer to:*Cadaver of a human, or carrion of an animal.*Carcass , a death metal/grindcore band*Carcass , a type of incendiary ammunition designed to be fired from a cannon, three ships of the Royal Navy...

.

They are commonly found at wholesale

Wholesale

Wholesaling, jobbing, or distributing is defined as the sale of goods or merchandise to retailers, to industrial, commercial, institutional, or other professional business users, or to other wholesalers and related subordinated services...

 fish markets in Japan, the largest of which is the Tsukiji fish market in Tokyo. They may be found at very large restaurants, but they are not used in a regular Japanese kitchen

Japanese cuisine

Japanese cuisine has developed over the centuries as a result of many political and social changes throughout Japan. The cuisine eventually changed with the advent of the Medieval age which ushered in a shedding of elitism with the age of shogun rule...

, unless there is a frequent need to fillet tuna with a weight of 200 kg (440 pounds) or more.

To those unfamiliar with Japanese knives they may be confused with Japanese swords. However, they are not a weapon but a tool, although they have been used as weapons by Yakuza

Yakuza

, also known as , are members of traditional organized crime syndicates in Japan. The Japanese police, and media by request of the police, call them bōryokudan , literally "violence group", while the yakuza call themselves "ninkyō dantai" , "chivalrous organizations". The yakuza are notoriously...

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