Seita is a kid who makes his living through pickpocketing. One day Seita picks Gintoki’s wallet only to find it pretty much empty, and discovers that his own wallet was picked back in return. In the end Seita treats Gintoki to some parfait after getting caught red-handed. Brought into Snack Otose for questioning, Seita shocks everyone by revealing he needed the money to see a certain “遊女/Yujo (courtesans/ prostitute).”

Seita was picking pockets to see Hinowa, the highest-ranked 遊女/Yujo (courtesans/ prostitute) in the underground 遊郭/Yukaku (Licensed Quarters) Yoshiwara Tougenkyo, where law has no meaning. But his picking act was all for the sake of seeing the mother he was separated from at a young age. To let Seita see Hinowa, Gintoki and the gang march into Yoshiwara Tougenkyo, where they receive a rough welcome by Tsukuyo – the head of Yoshiwara’s paramilitary force, “Hyakka.”

Kagura’s older brother Kamui arrives in Yoshiwara. As the Seventh Division Captain of the Space Pirate Harusame, Kamui is here to talk with the division’s former captain, The Night King, Hosen. At first everything seems to go well, but tensions gradually start to build up… Meanwhile, escaping from Kamui and his men’s attack, Gintoki and the gang take refuge at Tsukuyo’s hideout.

As Gintoki and the gang head toward Hosen’s lair, they encounter Abuki, one of Kamui’s subordinates, and are overwhelmed by the incredible fighting power of the Yato Clan. On Shinpachi and Kagura’s urging, Gintoki heads out to face Hosen alone. The remaining two fight desperately against Abuki, only to be cornered by the overwhelming difference in power. In the midst of the fierce battle Kagura renews her feelings toward her older brother Kamui and her reason for fighting. But with Shinpachi’s life in danger, Kagura goes through a dramatic transformation…

Amidst the fierce battle, Kagura awakens to her Yato instincts and defeats Abuto. Thanks to Shinpachi’s desperate plea, Kagura is able to return to her senses and together they head after Hosen. Meanwhile Kamui has brought Seita before Hinowa, who is confined to her quarters. “Mom, let’s go home together!” Seita shouts out to his beloved mother. However, unexpected words leave Hinowa’s mouth…

Gintoki arrives before Hosen, just in the nick of time. To restore the bond between mother and son that has been torn by the city of eternal light, Gintoki engages Hosen with fierce determination. But against the King of the Night’s awesome powers, Gintoki is beaten helplessly to the ground. “Go home to the world above with your mom…” Taking to heart the words left by Gintoki, Seita tries to escape from Yoshiwara with Hinowa, but…

The only way to defeat Hosen is to bring back the Sun to the Yoshiwara Shangri-La, the city trapped within eternal night. Seita runs for the control room to break open the iron-plated seal covering the city. Meanwhile, Gintoki and the Hyakka led by Tsukuyo are desperately holding off Hosen’s attack. But despite their best efforts, they cannot stop the King of The Night’s onslaught…

At last the sun rises above Yoshiwara Shangri-La, the city of eternal light. At the end of a fierce battle, Hosen finally reveals his true feelings for Hinowa and passes away. Observing the entire battle from afar, Kamui is greeted by Kagura and Shinpachi. Kagura is enraged with her reunited brother, but Kamui leaves after “declaring war” with Gintoki.