Kao (花押) were stylised identification signatures used on important papers by the lords and nobility of Japan since the Heian Period.
（Toyotomi Hideyoshi‘s Kao)
The reading and identification of the many Kao was difficult, and so books showing samples of the
various daimyo’s Kao were produced.
（Oda Nobunaga‘s Kao）
Some politicians, traditional artists, celebrities and persons of note use Kao even to this day in place of a signature or autograph. Kao collectors scour antique shops and markets seeking new and interesting
Kao of Japan’s historical figures.