Set in the aftermath of the Russo-Japanese War in the early 20th century, the story follows Saichi Sugimoto, a battle-hardened veteran known as 'Immortal Sugimoto.' While searching for gold in Hokkaido to support the family of a fallen comrade, he discovers a map tattooed onto the backs of escaped convicts from Abashiri Prison. The map leads to a massive hidden fortune stolen from the Ainu people. Sugimoto forms an unlikely alliance with Asirpa, a young Ainu girl who is a skilled hunter and tracker. Together, they navigate the harsh wilderness of Hokkaido, facing off against the Imperial Japanese Army's 7th Division, ruthless outlaws, and other factions desperate to claim the treasure. The series is renowned for its blend of historical detail, survivalist action, dark humor, and deep exploration of Ainu culture and traditions.