Sugimoto's obsession with gold stops mattering the moment you realize he's actually trying to save a kid who's already decided she doesn't need saving. Season 4 forces every character to reckon with what they've sacrificed for a treasure that was never the real prize. The comedy still lands, the survival details still grip you, but underneath it all is this quiet devastation: Asirpa has grown up, and Sugimoto is finally understanding what that costs.

Sugimoto the Immortal and Asirpa press on in the race for the lost Ainu gold, which is now nearing its climax. Ever more dangerous ex-convicts are determined to keep their tattooed skins intact. Asirpa's time with Kiroranke and Ogata has shifted her goals and hardened her resolve, and as the party leaves Russian territory they pick up a peculiar follower. Hijikata's crew makes bold moves to secure valuable skins but falls into a poisonous trap laid by a dangerous convict. Former head jailer Kadokura joins the hunt as well. First Lieutenant Tsurumi, the most powerful and ruthless contender, still cannot advance without Asirpa, and what he plans for their eventual meeting remains unknown.