 ""Kimi"" has been used either as a noun to indicate an emperor or one's lord (i.e., master) since at least the Heian period.For example, the protagonist of "the Tale of Genji" is also called .But before the Nara period, the emperor was often called ""opokimi"" (great lord); so it is controversial whether or not the word ""kimi"" in ""kimigayo"" had meant emperor originally.