When Looking for Something You've Lost, Remember What You Were Doing on the Day You Lost It (無くした物を探すときはその日の行動をさかのぼれ, Nakushita mono o sagasu toki wa sono hi no kōdō o sakanobore) is the fifty-seventh episode of the Gintama anime.
Mutsu requests the Yorozuya to recover some stolen cargo.
A surreptitious trade between Mutsu's group and a group from the Aoi Corporation goes awry when the money and merchandise are stolen by thieves. The following day Mutsu hires the Yorozuya to get the merchandise back. She explains that the merchandise stolen were a bunch of Soopah-Powah Batteries. Instead of heading to the Aoi Corporation to question them about the recent theft. The Yorozuya head to Snack Smile and meet and drag Sakamoto out of the place. The group discusses the battery theft with Sakamoto at a coffee shop, who has no clue about it as he always lets Mutsu handle all of the details.
The following day the Yorozuya with Sakamoto head to the Aoi Corporation and discuss with the president about the recent Soopah-Powah Batteries theft. The discussion gives them no leads. That evening, instead of continuing with their search for any more clues, the group goes to a bar and Gintoki and Sakamoto get drunk. As the group head home, they've ambushed the thieves responsible for the Soopah-Powah Batteries theft. Sakamoto using a single shot from his laser gun scares the Jouishishi away. Gintoki and Kagura beat up Sakamoto for his actions as they lost any clues that would help identify the thieves. It's at that moment that the President of the Aoi Corporation along with two representatives approach the group.
At Yorozuya Gin-chan the President of the Aoi Corporation divulges new found information he has on the thieves. The name of the organization association is simply called, "Evil Organization". The next day, the Yorozuya and Sakamoto go to the Evil Organization HQ and are confronted by the organization's army and leader. The leader turns out to be someone that Gintoki faced off against in the past and he swears vengeance against him. Amid the sequential fight that occurred after the Yorozuya defends themselves against the Evil Organization army. Sakamoto, on the other hand, can't fight as he's misplaced his pistol. Gintoki then gives Sakamoto a gun given to him by Mutsu and instead of using it, he disassembles it.
With the tide of the battle turning against them, the evil organization brings out the modified Neo Armstrong Cyclone Jet Armstrong Cannon. A cannon powered by the Soopah-Powah Batteries stolen during the business transaction between Mutsu and the Aoi Corporation. Finally, Sakamoto finishes assembling his gun and is perplexed as to why there's no one around. While running for his life, Gintoki grabs Sakamoto and saves him from harm's way from the giant mobile NACJAC. Sakamoto finds the weak point of the NACJAC and when he tries to fire it, it turns out to be not only a toy gun but also a transmitter. The Kaientai arrives on the scene and take out the NACJAC.
The aftermath of the even reveals that both the Soopah-Powah Batteries and the money is missing. The leader of the Evil Organization has no clue as to where they might be and Mutsu figures during the chaos the items were stolen. Later that night, Mutsu and the Yorozuya confront the Aoi Corporation President and his associate about the missing loot and merchandise. As it turns out they stole the Aoi Corporation in order to gain a lucrative profit. Mutsu thanks the Yorozuya for their help and pays them for their services, all while Sakamoto tries to hit it off with Oryu again at Snack Smile.
- When the Justank appears, the "Imperial March" theme from the Star Wars saga starts playing.