Season 1

Sugimoto Saichi, called "Immortal Saichi" for his incredible powers of survival, is panning for gold in the far north when he hears a story about buried treasure, hidden by a death row inmate. He decides to go after the treasure, but it will be a journey far longer and far more dangerous than he'd ever imagined...

Saichi and Asirpa head to Otaru, the largest town in the area, in seach of the tattooed prisoners. They quickly find out that they're not the only ones after the treasure. The army is looking for it too! Saichi has to face off against a deadly sniper, and a horrible cold front is setting in too...

Sugimoto and Asirpa are pursued by soldiers from the 7th Division. Private Genjirō Tanigaki finds Asirpa, but is fought off by Retar. Sugimoto evades capture after diving into a bear cave, whose occupant charges and kills the soldiers before succumbing to its wounds. Sugimoto and Asirpa take a baby bear found in the cave to Asirpa's village, and visit Asirpa's grandmother ("Huci"). Lieutenant Tokushirou Tsurumi, the leader of the 7th, mounts a search effort for the missing soldiers. Meanwhile, at a brothel in Otaru, Hijikata ambushes the tattooed prisoner Ushiyama Tatsuma, and offers to work with to him collect the tattooed skins.

Sugimoto leaves the village and returns to Otaru alone, where he learns of the incident with Ushiyama. He is captured by Tsurumi, who accuses him of killing the soldiers. Asirpa and Retar track Sugimoto and find Shiraishi, who tells her Sugimoto's location.

Sugimoto is tortured by twin brothers Youhei and Kouhei Nikaidō. Shiraishi breaks into Sugimoto's cell and releases his bonds, allowing him to kill Youhei. He fakes a fatal injury using Youhei's intestines, and is able to escape and reunite with Asirpa. While hunting, Asirpa and Sugimoto come across the tracks of two men: Tanigaki and Tetsuzō Nihei, a famous bear hunter.

Nihei tells Tanigaki that he wishes to hunt Retar, the last Hokkaido wolf. Asirpa and Sugimoto are joined by Shiraishi, who tells Asirpa and Sugimoto that Nihei is a tattooed prisoner. Asirpa, Sugimoto and Shiraishi track the hunters and ambush them.

Sugimoto and Shiraishi fight Nihei, while Tanigaki captures Asirpa. Tanigaki is shot by a poisoned arrow after stepping in a deer trap, but is saved by Asirpa. Retar rushes to Asirpa's aid with his mate, a grey wolf, who attacks and kills Nihei. Tanigaki is brought to Asirpa’s village to recover, and tells them that Tsurumi intends to use the gold to mount a military coup to form an independent Hokkaido. At a brothel, Ushiyama finds Shiraishi and gives chase.

Caught by Ushiyama, Shiraishi is pressured by Hijikata into acting as his mole in Sugimoto’s group. Sugimoto, Asirpa, and Shiraishi hear rumors of Henmi Kazuo, a tattooed prisoner who is also a psychopathic killer. They go whaling and unknowingly rescue Henmi after he falls into the water. Henmi conceals his tattoo, but vows to either kill Sugimoto or die in the attempt.

Hemni and Sugimoto are confronted by 7th Division soldiers. As they flee, Hemni attempts to kill Sugimoto, and they engage in a violent struggle before Sugimoto fatally stabs him. An orca beaches and grabs Hemni’s body, though Sugimoto, Shiraishi and Asirpa are able to recover it. Meanwhile, Ogata and Nikaidō find Tanigaki at the Ainu village, and accuse him of killing his companions and deserting the 7th. Tanigaki realizes that are battling factions within the 7th, and prepares to defend himself.

Tanigaki, a Matagi, escapes his pursuers by using his skills in hunting and trapping. Tsurumi arrives, and forces Nikaidō to expose the traitors in the 7th after cutting off Nikaidō’s ear, though Ogata evades capture. Elsewhere, Shiraishi is grabbed by a massive huchen after falling in a river, but is saved by Kiroranke, a former friend of Asirpa’s father. Kiroranke reveals that Asirpa's father is Nopperabo, and that he is now in Abashiri Prison. They begin to travel towards Abashiri to confront Nopperabo.

The group and Ushiyama separately check into a hotel run by Ienaga Kano, a tattooed prisoner who murders and eats her guests. Shiraishi and Ushiyama are held in a basement torture chamber while Ienaga attempts to kill Asirpa, but is thwarted by Sugimoto. A series of events triggers an explosion that destroys the hotel, burying Ushiyama and Ienaga in the rubble. Sugimoto's group continue on to Abashiri Prison.

Shiraishi meets Ushiyama and Ienaga, who survived the explosion, but does not disclose this to Sugimoto. Sugimoto’s group encounter Inkarmat, a traveling Ainu fortune teller who Asirpa does not trust. Shiraishi takes Inkarmat to a horse race, where they win two races on Inkarmat’s predictions. Kiroranke meets old friends at the track, who ask him to ride a horse and throw the race at the behest of a yakuza boss. Shiraishi bets all his money on the last race, but it is won by Kiroranke, who defies the yakuza boss. In Barato, Ogata meets with Hijikata and joins his group.