Origins of the Coloring pictures in Japan
Coloring pictures are thought to have originated in the Meiji Era when the government decided to incorporate Western culture into Japan, and introduced foreign music, sports, and fine and applied arts. The Meiji administration used examples of imported art from Europe to teach art to Japanese children. The children practiced drawing by tracing and copying the outlines from the book, similar to the copying of model characters that they did and still do when studying traditional calligraphy. After they traced outlines of art works, they colored them in. This is how coloring started in Japan.
In the latter half of the Meiji Era, contests were held to determine the best hand-colored postcards, and prizes were awarded to the winners. During the Taisho Period, coloring pads appeared, and with the wide distribution of crayons, coloring pictures quickly became popular.