The power source of the brothel
First of all, the elevator. While primitive animal- or man-powered lifts and hoists had been in use for ages--there was even one in the Roman Coliseum-- this looks and operates like an Otis-style hydraulic or at least counterweighted elevator, of which there's no known example earlier than 1743 (Louis XV commissioned it for his personal chambers in the Palace of Versailles). The hydraulic elevator is generally said to have been invented in the 1800s and was firmly established by Elisha Otis' invention in 1853 of the safety brake. Using the Versailles example, the brothel's lift is just marginally possible, but very iffy, considering Japan's total isolation from the West at this time.