Episode 4: Hellhounds for Hire (Part 2)/Tacit Understanding:

Yakuza boss Rikiei's shades (seen also in Ep. 3).Might just as well be Oakleys. Neko-san points out that Rikiei's glasses are not only stylistically wrong for his era, but technologically unlikely as well: "Irregularly-shaped lenses (Jin and Reikiei both have them) are also a bit too modern, because in those days lens-grinding was pretty difficult and time-consuming. Irregular lenses are not easy to center properly. Glasses were not normally tailored to a prescription, either. You basically just tried on pairs of varying strength until you found something that worked."

Rikiei's metal nail file. Best info I can find says that these weren't invented till 1900. Prior to that people cut their nails with scissors and shaped them down with anything from sandpaper to acid (!).

The dice. We wondered if dice in this form were a modern invention, but heck no: cubical dice with impressed numbers have been around for thousands of years. Especially note the big red spot on the dice Fuu uses in the gambling hall: Chinese and Japanese dice have had the numbers 1 and 4 as large red markings since the Ming Dynasty. Incidentally, as best I can tell, the ones on Fuu's tanto are the same. ---Here's a little on the history of dice in the East.

Traditional Chinese dice.