Cleaning the Toilet Cleanses the Soul (便器を磨く事これ心を磨く事なり, Benki o migaku koto kore kokoro o migaku koto nari) is the one-hundred and thirteenth episode of the Gintama anime.
Okita and the First Squad are in charge of cleaning the Shinsengumi headquarters’ bathroom for the week. Everyone mutters complaints as they polish toilets. But one man happily works without complaint. It is Seizo Kumanaku, who is well known within the Shinsengumi as a neat freak. He lectures his squad mates about the importance of a clean bathroom, but it fails to raise their spirits. Seizo is irritated by how dirty the toilets are and he suggests to Hijikata that they have a Bathroom Revolution.
At the Shinsengumi base, Hijikata delegates the cleaning assignments to the squadrons. Cleaning the toilets, the most mortifying assignment was delegated to the 1st squadron Okita's. As vexing as the assignment was, the squadron performs their cleaning duty. One member a new recruit named, Kumanaku Seizou notes the cleanliness paragon of their assigned task. Feeling inspired by Seizou's speech, Okita scrubs off Seizou's mole and flushes it down the toilet. With Seizou distracted in trying to retrieve his mole, the rest of his squadron bail. Okita the only person left behind, asks if they should stop too. Seizou, on the other hand, insists they stay and finish cleaning noting the nasty habits their co-workers commit in the restrooms. He, therefore, implores that the Shinsengumi must wage war against the germs that surround their base.
The matter is brought to Hijikata's attention who initially rejects the ideal favoring eliminating the Jouishishi instead. He's, however, convinced otherwise by A candid argument from Seizou involving washing your hands after touching your "Thing". What further corroborates the matter is witnessing bacterial hallucinations coming from his fellow Shinsengumi. And thus, Hijikata joins, Okita and Seizou in the Toilet Revolution. They first try and find solutions for the members to aim properly when they use the urinals, to prevent urine from splashing everywhere. So Okita uses Seizou's mole as a target and discloses that he feigned flushing it down the toilet before. A photograph of Hijikata is then suggested, much to the person's chagrin. It's at that moment that the trio hides in a bathroom stall and see if their plan worked. Instead of urinating in the urinal with the picture of Hijikata on it, they took a dump. Another urinal with a picture of Hijikata had a gaping hole in its face. Okita then proposes they devise a way to make it impossible for urine to splash on the floor.
At that moment, a member enters the restroom and Seizou and Okita lay on the floor dressed in school outfits. The scenario to that was they were two friends who just fought with one other and are impressed by their opponent's caliber. This prompts Hijikata to violently reprimand the two. Pressing forth with another idea, Okita drills holes into a large wooden plank and draws women's faces on it. This is so the members will be able to aim properly and feel enlightened to do so. Vehemently against it, Hijikata asks if Seizou agrees who thinks the holes should be bigger. They then hear someone coming and hide in one of the bathroom stalls. After 5 minutes pass, the trio sees what's taking the person so long and it's Kondou who got his thing caught in the hole. Witnessing this incident, the trio leave in an orderly fashion.
Yamazaki then writes a report on the bacterial usurpation outbreak of the Shinsengumi HQ. The source of the outbreak was none other than Kondou and it spread all across Ooedo. In a last-ditch effort to save the world from the bacterial monsters. The Shinsengumi lead by Hijikata spearheads the last defense against the monsters. This entire incident, however, was just part of Hijikata's dream.