Manga by Satoru Noda.
In Hokkaido, the far northern lands of Japan, Saichi Sugimoto survived the Russo-Japanese War of the Meiji Era. Nicknamed "Sugimoto the Immortal" during the war, he now seeks the riches promised by the gold rush, in hopes of saving the widow of his now-deceased comrade. During his hunt for gold, he finds out about a massive stash of gold hidden by a criminal. Partnering with Asirpa, an Ainu girl who saves his life from the harsh climate of the north, he battles against the criminals, the military, and nature itself to find the treasure!