One of the five subcastes of the senmin lower class (which consisted of Ryoko, dedicated to the imperial family or guards of imperial tombs; Kanko, dedicated to public ministries; Kenin, servants of high-ranking families; Kunuhi, slaves of the court; and Shinuhi, slaves of families) that existed under the ritsuryo system.
律令制における五色の賤（陵戸・官戸・家人・官（公）奴婢・私奴婢）の一つ。