The voltage in Japan is 100V which is different from most other regions in the world and Japanese plugs are like the one above, two non-polarized pins.
There are two kinds of frequencies in use; 50 Hertz in eastern Japan (Tokyo) and 60 Hertz in western Japan (including Nagoya, Kyoto and Osaka).
The Shape of The Plug
Japanese plugs are type A. If you are using a different shape of the plug, you need to bring your own converter to use your electric appliances. And of course if you purchase Japanese electric appliances for your souvenirs, you should look for ones which are for oversea tourists.
AKKY International, Akihabara
They have a wide range of products, such as home electronics, Japanese folk crafts, cosmetics, watches and travel products.