There are no columnar-shaped plugs or 3-pin plugs used in Japan but 2-flat-pin plugs such as the one shown in the photo above are used instead. It is therefore advised to purchase a plug adapter beforehand.
The voltage used throughout Japan is uniformly 100 volts, A.C. There are two kinds of frequencies in use; 50 Hertz in eastern Japan and 60 Hertz in western Japan (including Nagoya, Kyoto and Osaka).
A convertible type of electrical appliance such as a hair dryer, travel iron and shaver will therefore be handy; otherwise a step-down transformer is required to convert the voltage.
In Japan, it is relatively easy to find devices such as conversion plugs and transformers in urban areas. They are sold in electronics quarters such as Tokyo’s Akihabara and Osaka’s Nipponbashi, or major home appliance mass retailers.
Electronic devices that you carry with you can be recharged with relative ease. Visitors to Japan usually do not have any problems with the outlets in hotels that they stay in. Furthermore, new Shinkansen models have outlets at the bottom of the walls by the window seats. If you would like such a seat, please consult the teller window. In recent years, some hamburger chains and family restaurants have shops with outlets by their seats.
Reference: © blog.livedoor.jp