Afterwards, "Suma" was assigned to the Japanese force which seized Sakhalin from Russia, covering landings by the IJA 13th Division at several locations, and securing lighthouses and port facilities. In August, her reconnaissance parameters were expanded to include the southern coast of the Kamchatka Peninsula and the Commander Islands, and was dispatched to Petropavlovsk-Kamchatsky to rescue retired Lieutenant Shigetada Gunji, who had been arrested by Russian authorities for his unauthorized private invasion of Kamchatka. While in the area, "Suma" also captured the United States-flagged steamer "Australia", which was found to be transporting war contraband.