In 2003, The Truth of the Chronicles of Japan [日本書紀の真実]was published. The author, Yuuko Kuranishi, proposes a landmark hypothesis that the Chronicles of Japan would be composed with plural year number tables, maybe five or six in all, each of which has different starting years. This plural structure suggests that some of year number tables should be duplicated so that the lifetimes of early Tennows would have been prolonged unnaturally.
