The Yorozuya spend time with a robot tinkerer preparing for a special festival, but his scars of the past force him under the manipulation of Gintoki's former ally Takasugi Shinsuke.
Katsura is confronted by his old friend Takasugi Shinsuke, who has been on the run trying to escape from the Shogunate. He has returned to Edo for a festival celebrating twenty years since the Amanto first arrived at Edo. Takasugi makes a remark about how terrible it would be if the Shogun's head would roll during the festival leaving Katsura in a shock. Back in Kabukicho Otose and the rest of the neighbours have gathered outside Gengai's garage, Edo's top inventor, because of the incredibly loud noise coming from his repairs.
The Yorozuya appear and start singing through a microphone in order to equal the noise. After a while a huge robot opens the garage door and grabs Gin by his head scaring off the rest of the neighbours. The Yorozuya enter the garage and tie Gengai before they start to pack his things in order to stop the noise. In the meantime, they interact with one of Gengai's robots, Saburo. They take all of the robot parts by the riverside and let him work on his repairs at that place. He informs the Yorozuya that he has been ordered by the Bakufu/Shogunate to have all of his robots repaired and make a show during the Shogun's rare public appearance at the festival. Next, we learn from a flashback that Gengai's son, Saburo, was tired from watching his father building robots only for the purpose of killing and he decided to join the Amanto war to get that grin off his father's face. The Shinsegumi make preparations at the same time for the festival in order to keep the Shogun safe from any terrorist attacks, especially from a certain man that once killed 12 Shogunate officers during a dinner meeting, Takasugi Shinsuke.
The Yorozuya spend the rest of their day helping Gengai to fix the robots for the festival. The time for the festival has arrived and Gintoki is having a conversation with Gengai about what happened during the Amanto war, with Gengai asking Gin if he ever thought of avenging his fallen comrades. Shinpachi, Kagura and Sougo are enjoying themselves in the festival, while the Shinsegumi are in alert to keep the Shogun safe. Gengai finally begins with his robot show by throwing some fireworks. It is at this moment that Gintoki is being ambushed by Takasugi, who turns out that he is a former comrade of Gintoki, Katsura and Sakamoto. Takasugi threatens Gin with a sword to stay on his position without making a single move telling him to "enjoy the show". Gengai's robots go frenzy and they march on attacking the Shogun and the Shinsengumi.
Takasugi informs Gin about how he manipulated Gengai to use his robots against the Shogunate taking advantage of his son's death during the Amanto war. Gintoki grabs Takasugi's sword with his bare hands completely immobilizing it and punches Takasugi. Meanwhile, the Shinsegumi are back-up'd with the enraged because of the festival's destruction Kagura and Sougo and turn the tide of the battle. Gintoki confronts Gengai and his robot, Saburo, asking him to stop what he's doing. Gengai orders Saburo to fire towards the Shogun even if Gin stands in the way. Gin proceeds to attack the robot and destroys it after noticing for a brief moment that the robot hesitated and lowered its weapon on its own free will.
Moments before ceasing to function, Saburo tells Gengai exactly the words that his son told him before he left for the war. The next day Katsura has a small conversation with Takasugi about how Gintoki still has the wild beast inside him as he did in the Amanto war and that Takasugi's sole purpose is to destroy everything, before noticing Gengai in the streets fixing small robot toys for the children.
- Sakata Gintoki
- Shimura Shinpachi
- Gengai (debut)
- Katsura Kotarou
- Takasugi Shinsuke (debut)
- Hasegawa Taizou
- Kondou Isao
- Hijikata Toushirou
- Okita Sougo
- Yamazaki Sagaru