Yoshiwara—a massive underground red-light district where the power of the law does not reach. A city of eternal night where desires swirl and the sun never shines. In Edo, Sakata Gintoki, who runs an "Odd Jobs" shop known as the Yorozuya, meets an orphan named Seita who makes a living as a pickpocket. Seita says he is searching for his long-lost mother, and believes that Yoshiwara’s top courtesan (Oiran), Hinowa, might be her.

The courtesans of Yoshiwara are under the control of Housen, the Night King. Among the combat-loving Yato clan, Housen boasts overwhelming strength; he has seized control of Yoshiwara's interests and enjoys vast wealth and power at his whim. "I just want to see my mom, even if it’s only for a moment." To grant the young boy’s small wish, Gintoki and his companions spring into action. Can their bonds illuminate this massive darkness?