Ōyama Iwao
Following the Meiji Restoration, Hayashi joined the new Meiji government. He was sent on a mission to Europe in August 1870 to monitor the Franco-Prussian War, and arrived in Berlin in October together with Ōyama Iwao, Shinagawa Yajirō, and Arichi Shinanojō. After his return to Japan in May 1871, he worked with Itagaki Taisuke but resigned in 1873 due to his disagreement with government policy in the "Seikanron" debate. He returned to Kōchi but was later arrested for supplying arms in support of Saigō Takamori in the Satsuma Rebellion. One of the leading advocates of the rebellion, Hayashi also planned to seize a Mitsubishi steamer and attack the government arsenal at Osaka. For these actions, he was sentenced to ten years in prison.