Since FUJIWARA no Tametaka was a real brother of Shigetaka, Tomotaka and Chikataka, there was a possibility that the history of the book had been handed down in the Bojo family, but the truth remains unclear.
藤原為隆は重隆・朝隆・親隆の実兄であり、坊城家にかつてその由来が伝わっていた可能性もあるが、不詳である。