Analysis of information sources in references of the Wikipedia article "Ninja" in English language version.
Goshiki-mai: These dyed rice grains were used to create discreet trails that could be followed either by the original dropper or by sharp-eyed comrades
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Based on the combination of colors they dropped, or the number of grains, the Ninja could make over 100 different codes.
What we can conclude from the writing is that it was already well-known among people in the end of Sengoku period that sneaking and making night attacks were Ninja's favorite tactics.
