존왕양이
In 1861, Chōshū domain hired Ōmura back to teach at the Chōshū military academy and to reform and modernize the domainal army; they too gave him the ranking of "samurai". It was this same year that Ōmura began his involvement with Kido Takayoshi, a political moderate who served as liaison between the domain bureaucracy and radical elements among the young, lower-echelon Chōshū "samurai" who supported the "Sonnō jōi" movement and the violent overthrow of Tokugawa rule.