When the Russian warship As-korid visited Nagasaki in 1858, Shinho was ordered to supervise it. He learned Russian from an officer of the warship and was informed of conditions abroad. He subsequently studied the language from Russians who visited Nagasaki, eventually becoming the top expert of Russian in Japan.
Shiga acted as an interpreter in Japan-Russian negotiatiom, held on various issues, including the invasion of Toushima Island by Russians in 1864. When the Shogunate sent a delegation to the Russian capital for negotiations to set the borderlines in the Sakhalin area late in 1866, Shiga accompanied it. The delegation arrived in Petrograd in 1867 and signed a provisional agreement.
After the Meiji Restoration, Shinho served in the Foreign Office. He was appointed chairman of the reception committee for Russian Prince Alexei who visited Japan in 1871. Shiga was in Russia (1873-1875) for negotiations for the exchange of the Kuriles with Sakhalin. Shinho retired from government office in 1877.