Kagi kento (L-mark) and hikitsuke kento (straight mark) are L-shaped and straight-line registration marks that are carved on the woodblock as markers for accurately placing the paper in the correct position for printing.

The L-mark is carved on the bottom right corner while the straight mark is carved around two-thirds of the way across the bottom edge (including the margin on the paper) to the left of the L-mark. When printing, the paper is held between the index and middle fingers of both hands. The bottom right corner of the paper is then rested against the L-mark and pinned in position using the thumb of your right hand, and the bottom edge of the paper is rested against the straight mark and pinned in position using the thumb of your left hand. Finally, the paper is gently lowered over the printing block. The marks thus enable the paper to be placed in the correct position so that even when multiple printing blocks are used there is no color drift or displacement.

When carving out registration marks, calculate the size of the image and margin of work and mark them directly on the woodblock first. If the registration mark to indicate the outer edge of the margin will fit inside the woodblock, mark the position of the L-mark on the lower right and that of the straight mark on the lower left, directly on the woodblock. Putting registration marks on the woodblock you are carving in this way is called “uchi kento”. If the size of the woodblock is going to be the size of the image, then you must prepare a wooden board that is the same thickness as the woodblock and carve registration marks on that. This board is called “kento-ban” and the method that involves the use of this board is called “soto kento”. The registration marks should be cut out in a perpendicular direction to the woodblock using a tool called the kento chisel. A cutter can be used instead if a kento chisel is not available. Using a flat knife, carve a slight slant on the registration marks to create a shelf that is deep enough for the paper to rest on. Take care when doing this because if the L-mark is not at right angles, or if the straight mark is not aligned in a straight line with the line extending from the bottom edge of the L-mark, this could cause color drift when the different colored printing blocks are applied.

Generally, the L-mark is on the right-hand side and the straight mark on the left. But they can be placed the other way round if you are left-handed.