 Nichiren also predicted a foreign invasion, which a prediction which came true more than a decade later when Japan was invaded by the forces of Kublai Khan.Endō Asai, in his article on the work for the "Encyclopedia Nipponica" remarks that because of its status as a polemic against the religious practices of the nation, it lacks an explanation of the causes that lead to its conclusions, and recommends reading it in combination with "Shugo Kokkaron" (守護国家論), which Nichiren had published the previous year.A copy of the text in Nichiren's own hand, dating to 1269, is preserved in Hokekyō-ji in Ichikawa, Chiba.