You can plug pretty much anything you bring into any outlet you find in Japan. The voltage is a bit lower but not enough to matter. The frequency is a bit lower in the north/west of the country (Tokyo, Hakone). There it’s 50hz vs the 60hz we’re used to here in the states). In the south/west (Tajimi, Kyoto), it’s the same 60hz as here in the US. What does that mean in practical terms? Anything with a motor will run a bit slower …. your hair dryer for example. Otherwise, you’ll probably never notice any difference. The outlets are all for two-prong plugs. If your gadgets have a third round grounding plug, you’ll want to bring an adapter. You can find them for under a buck at any hardware store or probably even at Kroger. The rooms we stay in won’t have many outlets, so a small triple-outlet adapter will be useful, especially if you’ve got more than one or two gadgets. Remember, your roomie might need to recharge too. If you’re planning on buying any electronics in Japan, make sure it’s intended for use in the US. FM radios, for example, are a bit different; ours don’t work there. Theirs don’t work here.