After a very long wait, I just posted Lesson 35 of Water Business at Manga Fox. I'm pretty sure I didn't make any huge mistakes in my translation, though it is a very free one in places.
I have also acquired a copy of the novel Toritsu Mizushō! by Hikaru Murozumi. I'm not going to be posting a translation of it; that much Japanese is too much for me. But I am sort of deciphering what I can of it; I've already OCR'd it and searched it for character names to find out who's in and who isn't.
One thing that the manga series completely skipped over was the "off-campus-training" for the fūzoku girls. Inokuma had been building up to it at least to Volume 20, but then the storyline jumps over nearly the entire third year. There is a chapter in the novel covering it, but it's only a few pages and it's all exposition--no action scenes, not even any dialogue. It all takes place in six days during the break between the end of the second year and the beginning of the third.
I was pretty disappointed the way Inokuma handled it. He may have had no choice in the matter; the series was cut short by the end of its magazine. Maybe he was ordered to avoid the subject. There's been a lot of noise about "cleaning up" Kabukichō over the past few years; the demolition of the Koma Theater is supposed to be part of it (although I fail to see how closing down the only venue for actual kabuki in Kabukichō would hurt the sex industry.)
Why am I so disappointed? Because the tension between Mari Oda and Daichi Nagasawa over her actually doing sex work was never properly resolved. It was a big plot point: Could a sex worker go on to have a satisfactory marriage? How difficult would it be to dispel the stigma? Dispelling the stigma of sex work and the rest of the Water Trade is, after all, the entire mission of The School of Water Business. It's just a bit more than a comedy.