Can I use a power adapter designed for USA in Japan?
I'm about to travel to Japan (from UK) and can't seem to buy a mains adapter that specifically says it can be used in Japan. However, the internet (e.g. Wikipedia) tells me that Japanese power sockets "appear physically identical" to US ones (although they use a different voltage), so I'm wondering whether I can use an "international adapter" (e.g. this one, with very a useful USB charging feature and multiple socket types) that can be used in the USA, or whether I'll have to wait til I get to the airport and pay more money for it.
Do you already own such an adapter or are you planning to buy one? In my experience this stuff is likelier to be cheaper in Japan than in the UK. Transport and accommodation are expensive there but a lot of other things are surprisingly reasonable, some things are even cheap!
I was planning to buy one - I'd prefer to buy before I go even if it's a bit more expensive, because my phone and computer both have short battery lives, and I'll need to charge them when I get to my hotel in the evening, before I'll have a chance to go shopping. I'll bear that in mind though!
Travel adaptors, especially ones that make claims about "wordwide" or "universal" ought to work everywhere. Look for reputable companies, or sites giving reviews of such products. But I'd expect unless it seems like a pretty junky item it should work fine especially with gadgets that are also designed to travel like laptops, phones, tablets, etc.
@Random832 just chargers for my phone, laptop, hair clippers and ebook reader. I checked that all of them can handle the 110 volt supply; one slight complication is that most of them have a UK plug but the hair clippers have a European one. I already went ahead and bought the charger I linked to in the question, as the people in the shop said it should work in Japan, and it can do everything I need.
You need to distinguish between the physical plug shape and the voltage requirements of the device that you want to plug in.
If you have an adapter that is made for the USA, then yes, in most cases you will be able to plug in that adapter in terms of physical shape into sockets in Japan.
However, you will have to check with each device that you want to use if they support the voltage and mains frequency that you get in Japan out of the power socket. If the label on the device says for example 100-240v, 50/60 Hz (as it says on most laptop power supplies), it WILL work in Japan. If it says 110... or only 240v, then there is high chance that it will NOT work in Japan. Also, you must consider that different parts of Japan use different mains frequencies: 60 Hz which is used in the USA, and 50 Hz which is used in Europe.
The good thing when going from Europe (240v) to Japan (100v) is that you most likely will not ruin your equipment if you plug it in and it cannot work with 100v. The other way round would fry your device in most cases. If you plug it in, it will simply work - or not. If not, you can still try to get an alternative device in Japan for the time you are there. As a very basic rule of thumb: items that have a high ampere requirement (hair driers, toasters etc) will not work. Items that are made to be portable or for travel work in most cases. Check the sticker on the power supply for the "input power" requirements.
Just to confirm for future reference, the international adaptor I mentioned in the question works perfectly in every Japanese socket I've ever came across.