The Kaishin-saku series is an affordable yet extremely performant line of Japanese traditional knives forged in Sakai, Osaka prefecture.
Sakai has a long history of blacksmithing, and their work is of such quality that in March 1982, the Ministry of Trade, Economy and Industry of Japan designated Sakai cutlery as a National Traditional Craft.
The Deba is a single-beveled knife primarily used for cutting and filleting whole fish. Its thickness, and often a more obtuse angle on the back of the heel allow it to cut off the heads of fish without damage. The rest of the blade is then used to ride against the fish bones, separating the fillet.
The Deba is not intended for chopping large diameter bones.
These measurements are only of the blade length, not the whole knife as handles length vary.