Then in the final volume it switches to a plot focused save-the-world isekai full of fan service and violence which is serviceable at best. It still maintains some silliness but most of the toilet facts disappear and you're left with a pretty lackluster final encounter.
Despite this abrupt change in style, overall I'd say Dungeon Toilet still ends up being a pretty cute comedy about a main character obsessed with toilets. The fantasy setting allows Yotaro to explain modern and historical toilet technology and development to the inhabitants of this other world. His two party members - the knife wielding elf with a tail Gigi, and the water magic using sorceress Nurael - both are constantly exasperated with his non-stop trivia and constant need to experience all forms of toilets.
Being that most of the manga is a slice of life comedy, there isn't too much character development outside of the main cast of three. There are flashback to show how the party came together, and their individual backstories, but it's mostly fluff with a little drama thrown in. There are about 4-5 other minor characters who appear - another adventuring party, Nurael's master who taught her magic, and even a Demon King! These all mostly show up for gags.
Until the last volume. I don't know if the author ran out of toilet trivia, was forced to change up the formula to keep interest up, or simple wanted to have a narrative ending to wrap up the series. But the ending is one non-stop ride of plot with all the characters coming together, teleporting between worlds and ending in a final battle. There was a little bit of gore in the first two volumes, considering resurrection magic exists in this world which allows people to die and come back. But that really ratchets up in the final fight, and there's some intense body horror going on as well. It's pretty discordant with the rest of the mostly tame toilet pooping scenes earlier in the manga.
Despite being a comedy series, I would say it's more humorous than full of jokes. Most of the humor comes from Yotaro's obsession with toilets and how much he goes on about them and toilet related items like all the different ways to wipe. There are some slapstick chapters, but it feels more like an educational manga than a strictly silly one.
The art is quite nice. The characters are drawn in a chibi style, but with fairly detailed clothing and facial expressions. The action scenes are well done, albeit most of them very short. The backgrounds also have a lot of detail. Early in the manga this is sometimes a problem - it can be hard to distinguish between character and background in some of the environmental shots. This problem goes away by the second volume however. In the last volume the art seems a bit rushed and simplified, but also cleaner as a result. No major issues though. The real piece de resistance is the depiction of toilets. All of them are lovingly drawn in exquisite detail to show off the wonder of the crapper.
The translation and editing is quite good. It feels very professionally done. Most if not all of the onomatopoeia/sound effects are left in the original Japanese, and translations are added in for especially large or pronounced sounds, e.g. WAAAAA going across the whole page. You will be missing out on some however if you can't read Japanese. There's even a long bibliography at the end of each volume that lists all the sources for the toilet information used throughout the manga.
I enjoyed my time with Dungeon Toilet, despite the whiplash from the final volume. It still has a pretty satisfying and appropriate final few chapters to wrap everything up, and it's a very light read. If you find yourself wondering about toilets and want to learn more, it's a pretty fun way to do so. I'm sure the author would be very happy if you read it while on the toilet yourself.
Also, how did this of all manga get an official English print edition?
