Mainly over the Muromachi period and the Sengoku period (period of warring states), they were granted as an unofficial name of government post to vassals who had made military exploits and achievements by shugo daimyo (shugo were Japanese provincial military governors, that became daimyo, which were Japanese feudal lords) and daimyo (Japanese territorial lord) in the Sengoku period.
主に室町時代から戦国時代(日本)にかけて守護大名、戦国大名が武功や功績ある家臣に対して授けた非公式な官名。