The knife makers of Japan have proven a true global success story. And it's something that both Tokifusa Iizuka and Hisao Osaki – a blacksmith and a salesman and knife sharpener – have played an important part in, and continue to do so to this day. Whenever the world's top chefs slice a piece of tuna or eel for their sushi creations, there's a fairly good chance they'll be holding a "Yanagi" in their hand, originally made by these two specialists.

They live in neighbouring prefectures, in Gunma and Nagiita, and Sanjo City, where Tokifusa Iizuka plies his trade, is considered to be the knife-making capital of Japan. He is the "primus inter pares" ("first among equals") here, amongst around 30 knife makers in the region who produce their goods by hand. Iizuka lives a modest life in plain surroundings, and began his career sharpening razor blades.

His sons, Masayuki and Yoshihide, have also entered into the family business, and the three men work together to produce around 1,000 knives a year. That may not sound like a lot, but compared to industrial productions, hand crafting individual pieces is ten times more complex and time-consuming. The blade of an Iizuka knife is made of reinforced carbon steel, and is sharpened on water stone.

Visitors to knife and cooking forums speak of Iizuka's creations in revered tones, even describing them as pieces of art. In 2006, the master craftsman was invited to the Internationale Handesmesse (International Craft Trades Exhibition) in Munich, where he demonstrated the art of blade production personally. Long sashimi knives are Iizuka's particular speciality: they sit comfortably in the hand, do not bend and are breathtakingly sharp. The Dick company (www.dick.biz), which sells the knives in Europe, praises the blacksmith's work as "meeting the strict standards of traditional Japanese aesthetics".

Hisao Osaki and his wife Keiko grant Iizuka's knives pride of place in their display units. Continuing the family tradition, the couple run their own store in Maebashi, and the business is a Mecca for knife enthusiasts. Old illustrated books explain the craft of Japanes knife making, knives with long histories are lovingly stored in boxes and wrapped in cloth, and those with their futures ahead of them sit proudly in display cases.

At the rear of the store is a workshop where Hisao Osaki sharpens knives for the world's leading chefs. He sits attentively in yellow oilskins at his grindstone (which is the size of a cartwheel), while cold water flies around the room in all directions. Apparently, the secret of achieving the best possible edge is the angle between the grindstone and the knife, and according  to Hisao Osaki: "This should be no more than the width of two 100-yen coins on top of one another."