Aizawa Seishisai
, born , was a Japanese nationalist thinker of the Mito school during the late shogunate period. In 1799 he became involved in the compilation of the "Dai Nihon-shi" (Great History of Japan) being undertaken by the Mito school. In 1825 he wrote his "Shinron" ("New Theses"), a collection of essays that dealt with issues such as Tokugawa defence policy and how the ships were a threat to Japan. Aizawa also tried to describe conditions in the West and theorize why those states had gained so much control; in his opinion Westerners used religion to inculcate conformity in  the masses. He also claimed that Christianity was used by the colonial powers to subvert native cultures and governments by creating a fifth column that would collaborate with and facilitate military conquest by Europeans. He discussed the religious policies established by the Toyotomi government and continued by their successors, the Tokugawa shogunate, in this context. Furthermore, he believed that if Japan's way of life was to survive, it would need to take up its own state religion in order to prevent cultural assimilation via Christianization and discussed the concept of "kokutai" ("national polity") in this context. The "Shinron" would  become an important work for the "sonnō jōi" movement and his theory of the Kokutai would be developed by future thinkers. In 1840 Aizawa became the first head of professors of the Mito school's "Kōdōkan" but was forced to resign in 1844 when Tokugawa Nariaki resigned as domain leader. He later returned to the "Kōdōkan".