Deep beneath the surface of an alternate-reality Edo lies Yoshiwara, an underground pleasure district sealed away from the sun and ruled by the brutal and near-immortal Housen, known as the King of the Night. This isolated world of perpetual darkness is controlled by the Yato clan warrior, who maintains his oppressive reign through fear and violence.

The story begins when a young pickpocket named Seita steals the wallet of Gintoki Sakata, the silver-haired founder of the odd-jobs business Yorozuya. Rather than seeking revenge, Gintoki discovers the boy is stealing to fund a desperate search for his missing mother, Hinowa, once the district’s most legendary courtesan. Accompanied by his loyal companions Shinpachi Shimura and the superhumanly strong Kagura, Gintoki ventures into Yoshiwara to reunite the family.

They soon encounter Tsukuyo, the fierce protector of the district who leads the Hyakka vigilantes. She hides a painful past tied to a crushed uprising and a deep connection to both Hinowa and the tyrant Housen. As Gintoki and his allies navigate the treacherous politics of the red-light district, they become drawn into an open rebellion against the King of the Night.

The situation escalates further with the arrival of Kamui, Kagura’s older brother and a powerful commander of the space pirate group Harusame. His presence introduces a devastating family conflict, forcing Kagura to confront the violent legacy of their warrior race. What begins as a simple rescue mission transforms into a city-wide battle for liberation, as the residents of Yoshiwara rise up to shatter the chains of their artificial sky. The narrative builds toward a climactic confrontation between Gintoki and Housen, a fight that will determine whether the sunless city remains forever trapped in darkness or finally breaks free. The arc weaves together intense action sequences with themes of freedom, the bonds of found family, and the struggle against systemic oppression.