In episode 8 of Golden Kamuy Season 4, the team returns to Hokkaido and plans to find the gold themselves by stirring up a conflict between Hijikata and Tsurumi. The Ainu leader Nispa proposes a solution to their financial problems by suggesting they help a local kotan deal with a man-eating bear, a Wenkamuy, that is terrorizing gold miners near a river rich in gold and a precious metal called "white"—actually platinum.

During their search for gold, Sugimoto and his team encounter Heita, a gold miner who has unexpectedly grown wealthy by mining the platinum mixed with gold in the river. In a surprising twist, Heita is revealed to be a notorious criminal known as the "Brown Bear Man," haunted by his traumatic past, which is tied to the story of a Wenkamuy. Tormented by his dark history and the guilt of having driven a Wenkamuy to kill his own family, Heita has escaped his tortured conscience by assuming various false identities.

Sugimoto and his team attempt to help Heita confront his inner demon, discovering that Heita's inner Wenkamuy is a manifestation of his guilt and fears. His pursuit of gold led to the downfall of his family and his own transformation into a murderous "Wenkamuy." Heita believed that the only way to momentarily free himself from the Wenkamuy's obsession was by killing another person.

The episode culminates in Sugimoto engaging in an intense battle against Heita's inner Wenkamuy, leading to a climactic revelation. Sugimoto's victory allows Heita to finally face his past and find peace, serving as a powerful reminder of the importance of truth and the destructive force of greed. The complex narrative highlights the psychological depth of the characters and their struggles against inner demons, painting a grim picture of the consequences of greed and guilt.