Abstract: From the letter by the Japanese invaders collected by Jianchuan Museum, we can see clearly the Japanese soul has been severely poisoned and distorted, because the Japanese government trumpeted imperial concepts. To be controlled by imperial concepts, with the establishment of the system of whole nation being a soldier, Japan walked on the way for the Emperor of Japan to launch a war of aggression on other countries, which caused severe disasters to the Chinese people and the people of the world. That is the trace of Japanese militarism's historical development, which is to start from publicizing and exalting Imperial Concepts to establishing the system of whole nation being a soldier, and in the end it must be crazy to launch a war of aggression on other countries. Faced with a series of the Abe Cabinet's dangerous action from distorting history textbooks to lifting the ban on collective self-defense, the international community must be highly alert to prevent the world from reliving the tragedy which Japan launched a war of aggression.