In the early 1900s, following the Russo-Japanese War, Saichi Sugimoto diligently searches for gold in Hokkaido. Known as "Sugimoto the Immortal" due to his bravery in combat, this former soldier aims to amass wealth to honor a promise made to his deceased best friend: to take care of his family, particularly his widow, who requires medical treatment abroad for her deteriorating vision. One evening, an intoxicated acquaintance recounts a tale of a murderer who killed several Ainu individuals and stole a vast amount of gold. Before being apprehended by law enforcement, the criminal concealed the treasure somewhere in Hokkaido. Clues to its location were left in the form of coded maps tattooed on the bodies of his fellow prisoners, who were promised a portion of the riches if they could locate it.
Sugimoto initially dismisses the story but is compelled to reconsider when he finds the body of the drunken storyteller, marked with the same tattoos. Before he can process the discovery, a hungry bear attacks, intending to finish off its prey. Sugimoto is saved by Asirpa, a young Ainu girl whose father was among those killed. With Asirpa’s expertise in hunting and Sugimoto’s survival skills, they decide to team up and search for the hidden treasure. Asirpa hopes to recover what belongs to her people, while Sugimoto seeks to fulfill his friend’s final request.