The kento is a simple device by means of which the printer insures the register of the picture throughout the printing process. It has been employed for several centuries, and experience has proved it to be the best means for the purpose. The principle is to maintain with absolute exactness the width of the margin of every requisite block by means of two small projections, the kagi (key) and the hikitsuke (draw stop), which are cut directly on the block, as shown in Figure 1. These guides cut on the key block will be printed on the kyogo (proofs pulled from the key block) and therefore copies on every color block, keeping the margin the same width as that of the key block. The printer positions his paper so that its edges coincide with these guides during printing. The kagi is a right-angled guide at the lower right-hand corner of the block; the hikitsuke, a straight-line guide…at a short distance from the lower left-hand corner. To cut these guides, the carver uses the kento-nomi,(a 15mm chisel) the edge of which is strongly made with a wider angle and is perfectly straight. The kento-nomi is held by the grip in the right hand, resting upright on the board with its edge exactly at the line to be cut, in such a manner that the flat side of the tools is vertical to the surface of the board (Figure 2). Then it is pressed down to make a cut about one-eighteenth of an inch deep. After the necessary lines have been cut in this way, the space must be cleared with an aisuki(bull-nose chisel) of large size. The clearing must be very shallow and must produce a flat and smooth surface in order to facilitate the fitting of the paper during printing. The depth required is two to three times the thickness of the paper to be used. In making the kagi, the cleared part must slope very slightly toward the point of the right-angled corner. The hikitsuke is left in the form of a sort of step, the top of which is cut in a straight line. The detail of these two guides can be seen in Figure 3a and 3b.
Re-printed from Japanese Print-Making by Toshi Yoshida and Rei Yuki, c. 1966