At the Oedo-Onsen Monogatari in Odaiba, you can stick your feet into a warm bath and let these little freshwater carp feast on the dead skin cells. I was there yesterday, and this is my foot.
That's Kirsty on the left, Sally in the middle, me on the right.
When you first arrive at the place you leave your shoes in a shoe locker by the front doors. You pay the 2,500 yen admission fee and get a rubber wristband with a barcode sticker that they scan as you add things to your bill (the fish and other treatments like hot stone massage cost extra, and then there are the restaurants and gift shops, and a game area).
Next you pick out a yukata at the yukata counter (they are the belted robes we're wearing under our yellow jackets -- there were more than a dozen designs to choose from) and then you go into the locker room to change and lock up your stuff.
We went to Doctor Fish first, then relaxed in this garden onsen area, where there's shallow warm wading pool, with stones arranged along the bottom in different patterns, which I guess are meant to massage your feet.
Some rocks were more painful to walk on than others...
We also spent quite a bit of time soaking in the indoor baths, where all you have with you is your "humility towel," a small thing you hold to your chest and let hang down so you're not baring all while you're walking around. Then you fold it up and rest it on the top of your head while you soak. Feels funny at first, but, like the feeling of fish nibbling at your toes, you quickly get used to it!