Analysis of information sources in references of the Wikipedia article "Kuroko" in English language version.
The earliest pictorial reference to a ninja in black is a book illustration of 1801, which shows a ninja climbing into a castle wearing what everyone would immediately recognise as a ninja costume. However, it could simply be that it is pictures like these that have given us our image of the ninja rather than vice-versa. It is a long-standing artistic convention in Japan, seen today in the Bunraku puppet theatre, that to dress a character in black is to indicate to the viewer that he cannot see that person. To depict a silent assassin in an identical way in a picture would therefore be perfectly natural and understandable to the contemporary Japanese viewer, and need not imply that the resulting illustration is in any way an actual portrait of a ninja.
