Further, there is an opinion that Daio-ke had family name until the beginning of 7th century since there is a description in "Zuisho (Sui Shu)" Wakokuden (articles about Wa written in Sui) stating that the family name of Wakoku-o (king of Wa) is 'Ama' or 'Ame,' but because it is not a single letter family name seen in Chinese style, an opinion that 'Ama' or 'Ame' is not a family name is supported.
また、『隋書』倭国伝に倭国王の姓を「阿毎」（あま、あめ）とする記述があり、7世紀初頭まで大王家が姓を有していたとする考えもあるが、中国風の一字姓でないことから「阿毎」は姓でないとする見解が支持されている。