"Hell's Paradise: Jigokuraku" is set in the Edo period of Japan and centers on Gabimaru, a notorious ninja assassin known as "Gabimaru the Hollow." Despite his fearsome reputation, Gabimaru harbors a deep desire to escape his violent life and reunite with his wife, the only person who ever showed him kindness. Captured and sentenced to death, Gabimaru discovers he is nearly invincible, surviving multiple execution attempts. The shogunate offers him a chance at a pardon: join a perilous expedition to a mysterious island known as Shinsenkyo, rumored to hold the elixir of immortality. Gabimaru agrees, seeing it as an opportunity to secure his freedom and return to his wife.

The expedition is composed of other death-row convicts, each with unique skills, and their assigned Yamada Asaemon executioners, who oversee them. Among them is Sagiri, an Asaemon tasked with monitoring Gabimaru. The group ventures to Shinsenkyo, an island shrouded in myth and danger, where they encounter bizarre flora and fauna, as well as monstrous beings known as Tensen, who guard the island's secrets. The Tensen are enigmatic, god-like entities with immense power, capable of manipulating the environment and wielding deadly techniques. As the group delves deeper into the island, they uncover its dark history and the true nature of the elixir of immortality.

Gabimaru's journey is one of survival and self-discovery, as he confronts not only the island's horrors but also his own inner demons. His relationship with Sagiri evolves from one of mutual distrust to a partnership rooted in respect and shared purpose. Other key characters include Yuzuriha, a cunning kunoichi with her own agenda; Toma, a young Asaemon grappling with his role; and Chobei, a ruthless criminal driven by ambition. Each character's motivations and backstories are gradually revealed, adding depth to the narrative.

The story explores themes of redemption, the human desire for immortality, and the cost of power. As the expedition progresses, alliances shift, and the line between friend and foe blurs. The island itself becomes a character, its ever-changing landscape and malevolent forces testing the limits of the group's resolve. The series balances intense action sequences with moments of introspection, creating a compelling narrative that keeps viewers engaged. The stakes escalate as the true purpose of the expedition is unveiled, leading to a climactic confrontation that challenges the characters' beliefs and survival instincts.