Biten YASUMOTO argues that although ancient emperors described in the Kojiki and the Nihon Shoki are likely to be historical figures, descriptions about the practice of the imperial throne being passed down from father to son and the lengths of the emperors' reigns are highly dubious.
安本美典は古事記や日本書紀に記された古代の天皇の存在そのものは信じられるが、皇位を父子で継承した事と在位年数が信頼できないという説を唱えている。