 On his return to Japan, Yoshihara accepted a post at the Foreign Ministry as First Secretary, and was assigned as a liaison to the American Consulate-General in Japan.The following year, he joined the Ministry of Finance as Director of the Yokohama Customs Office.However, in 1874 at the request of Ōkubo Toshimichi, he joined Gustave Emile Boissonade and the Japanese delegation to Qing dynasty China in the negotiations leading to the Japanese Expedition of 1874 to Taiwan.