Emperor Keikō (景行天皇 Keikō Tennō) was the twelfth imperial ruler of Japan to appear on the traditional list of emperors. No firm date can be assigned to this emperor and he is regarded by historians as a "legendary emperor". This does not necessarily imply that no such person ever existed, just that there is insufficient material to assign him to a historical period. His Imperial Majesty, Emperor Akihito of Japan The Emperor of Japan (天皇, tennō) is Japans titular head of state and the head of the Japanese imperial family. ... His Imperial Majesty, Emperor Akihito of Japan The Emperor of Japan (天皇, tennō) is Japans titular head of state and the head of the Japanese imperial family. ...

His legend was recorded in Kojiki and Nihonshoki, but the accounts of him are different in these two sources. In Kojiki he sent his son Yamatotakeru to Kyushu to conquer local tribes. In Nihonshoki Keikō himself went there and won battles against local tribes. According to both sources, he sent Yamatotakeru to Izumo province and eastern provinces to conquer the area and spread his territory. Kojiki or Furukotofumi (古事記) is the oldest known historical book about the ancient history of Japan. ... Nihonshoki (日本書紀) is the second oldest history book about the ancient history of Japan. ... Prince Yamatotakeru or Prince Ousu was the Japanese legendary prince of the Emperor Keiko. ... Kyushu region, Japan Kyushu (九州) is the third largest island of Japan and most southerly and westerly of the four main islands. ... Izumo (Japanese: 出雲国; Izumo no kuni) was an old province of Japan which today consists of the eastern part of Shimane prefecture in the Chugoku region. ...