> ... I don't know what they have in Japan -- it could be 220 volts.

Wikipedia covers the unusual 100-volt a.c. electrical power situation
in Japan, http://en.wikipedia.org/wiki/Mains_electricity 

  "In Japan, the electrical power supply to households is at 100 V.
  Eastern and northern parts of Honshu (including Tokyo) and Hokkaido
  have a frequency of 50 Hz, whereas western Honshu (including Nagoya,
  Osaka, and Hiroshima), Shikoku, Kyu-shu and Okinawa operate at 60 Hz.
  To accommodate the difference, appliances marketed in Japan can often
  be switched between the two frequencies."

Peter Neilson