In the past, samurai contracts were sealed with keppan, a thumbprint sealed with the warrior’s own blood, cut by his own blade. The vermillion color of the Japanese seal comes from the blood of these keppan to represent the significance of their seal. There are two main types of vermillion inkpad: the common sponge-type inkpad and premium inkpads made from kneaded vermillion.
The kneaded inkpad keeps the original color for a long time and its impression does not get blurred. Because of its high quality, kneaded type vermillion ink is used for arts like painting and calligraphy.