According to Nihonshoki (Chronicles of Japan), after the death of his son Yamato Takeru no Mikoto, Emperor Keiko made a tour of various places in connection with his son's Eastern Expedition; when he visited the Ukishima no miya Shrine in the Awa Province, his courtier Iwakamutsukari no mikoto caught tuna and white clam to cook them for Namasu (a dish of raw fish and vegetables seasoned in vinegar) and presented it to the Emperor.
日本書紀によれば、景行天皇は皇子・日本武尊の歿後、その東征の縁の地を歴訪したが、安房国の浮島宮に行幸したとき、侍臣の磐鹿六雁命が堅魚と白蛤を漁り、膾に調理して天皇に献上した。