"Nihonsyoki" is a first history book in which we can find out a name of Nichira, who is a child of Japanese bureaucrat despatched to Baekje. "Nihonsyoki" says that he was invited to Japan to advise foreign affairs such as a conflict in Garak(Minama) but assassinated by a Baekje person. Shotoku Taishi did not hold reigns of government as regency at that time, so "Nihonsyoki" does not have an article that shows a relation between Nichira and him. But "Shotoku Taishi Denryaku", a biography whose original text was considered to have been edited in about 10th century, says that Nichira met Shotoku Taishi. So there is a considerable difference between "Nihonsyoki" and "Shotoku Taishi Denryaku". "Shotoku Taishi Denryaku" says that Nichira and Shotoku Taishi had met at China in a past existence, and that Nichira implied that Shotoku Taishi would try hard to make Buddhism prevalent in Japan. Such contents of "Shotoku Taishi Denryaku" are amplified more in "Shoborinzo", which is a biography of Shotoku Taishi edited in the Middle Ages. "Shoborinzo" alleged that Nichira had been an monk and come from Goguryeo, emphasizing the encounter of the two persons resulting from a cause and effect in the past. Like "Shoborinzo", "Taishiden" which is categorized as the enlarged versions of biographies of Shotoku Taishi describes the assassination of Nichira caused by a Baekje person as a punitive justice. These biographies don't keep the original form which "Nihonsyoki" had shown any more, going so far as changing the contents of "Shotoku Taishi Denryaku", which had been mainly referred to when writing a biography of Shotoku Taishi until 20th century. These instances suggest that the writers of the biographies of Shotoku Taishi in the Middle Ages could add new elements to original forms according to their thoughts instead of seeking exactitude.