Hidetada Tokugawa died suddenly and the death of the Shogun upset the Tokugawa system, and was concealed by a part of the Oku-cho. To top it off, Hidetada’s successor had not yet been determined. Originally, there should be no objection that the legitimate son, Iemitsu, succeeds as the third shogun. But a gap was beginning to grow between the Tokugawa Shogunate andToshikatsu Doi. Doi, who scrutinizes the cause of the general’s death, stealthily examines Hidetada’s stomach, but is suddenly caught by someone who appears. It was nne other than Shogun Yasunari, a shogun swordsman. His autopsy reveals that Hidetada’s death was due to arsenic.