Insho, which usually called “Inkan” or “Hanko”, works just like a seal on sealing wax in medieval Europe, that is, identification. Mostly made from stones, woods, horns and bones, and metals with flat surface with carved letters.
The difference of Japanese Insho from seals in old days is that everyone has at least one for his/her own. All the adults in Japan should register their own Insho to the city they live in, and all the companies in Japan, too. Insho is just crucial to social life in Japan.
The origin of seals is said to date back to some 6000 years ago, in ancient Mesopotamia. Pictures and letters were carved on the surface of cylindrical substance and were put on clay for identification and for showing one’s authority. Later in Asuka period, about 1600 years ago, seals were brought in to Japan from China and soon was adapted to the Taiho legal codes in 701.
Over time, Insho spread all around Japan and in Edo era (1603-1867) ordinary people started to use Insho since this kind of identification was required for trading. There also was a registration system similar to current one.
At that time, Tenkoku technique which carve Kanji characters in unique style on the small surface of Insho was introduced to Japan from China. Koshu Tebori Insho is also said to begin its production in Edo era, and the artisans absorbed the technique.
Japanese box trees, horns of water buffalo, and crystals are usually used for Koshu Tebori Insho. The artisans carefully but bravely carve complicated Kanji characters on the small surface of 1 cm to 2 cm diameters. Deciding the Kanji design is therefore so important that the artisans take good time to consult to their succeeded Tenkoku design books. Using various types of sharp chisels, the artisans make the Kanji realized by their hand.
Koshu is current Yamanashi prefecture, and the production style, all the related traders and artisans (including material producer and dealers) are gathered in this area, is also unique.
Koshu Tebori Insho was designated as Traditional Craft by METI (Ministry of Economy, Trade and Industry) in 2000.