1823 work A Secret Strategy for Expansion(宇内混同秘策) called for Japanese world domination, describing how China should be conquered via Manchuria. He suggested that the Japanese government embark on "colonial and agricultural undertakings" on uninhabited islands in the South China Sea. He also said that the Japanese government should take the Ryūkyū as a base to attack and capture Luzon Island by surprise, then use Luzon as a base for its "southward advance" to seize Java and other places, ultimately spreading its "military might" in Southeast Asia. He believed that Japan should "adopt suitable means of aggression and annexation" to "increase its national interests." This became the first draft of Japan's "southward advance" strategy.