Ancient Roman architect Lucius Modestus accidentally (and repeatedly) time travels to modern day Japan, where he tries to copy Japanese inventions/bathing culture in order to impress the ancient Romans once he returns home. It's a pretty weird concept, which starts out fantastically but gradually gets less interesting as the novelty factor wears off. It kind of feels like Yamazaki ran out of ideas, since some of the later scenarios barely have anything to do with bathing (namely, the chapter with the lady gyrating on a giant dick statue. Ok then)- kind of surprising that this has reached 5 volumes in Japan.
It's basically just a gag manga, though- character growth is non-existent and there's just the bare minimum of plot continuity to make this a cohesive story. Considering this, the fancy treatment it's getting from Yen Press (oversized hardcover, complete with color pages, glossy paper, and a spiffy mostly-translucent slipcover) is pretty weird, but appreciated- it looks amazing.