Let me just cut to the chase...yep you can use your Sony Notebook adapter in Japan. I have traveled to Japan some 20 times or so and have covered the country in my travels. The difference that your Mom was reffering to is in the plug on your adapter. You have a grounding plug. Three prongs..two flat blades and a round grounding plug. You need to get an adapter that converts the three plug to a two plug. Essentially it just eliminates the round grounding plug, they don't use them in Japan. You can get this item everywhere..Walmart..Target..Hardware Stores..etc...they cost all of a buck or less.
The only other thing you should know about the power in Japan is that the Japanese use 110 volt and we use 120 volt. Your adapter dosen't care about this little difference. If you look on the back of it you will see a voltage range that it covers. It can propably take up to 220 or 240 volts ..that's so you can use it in Europe...but that's a whole different can of worms.
Enjoy your trip...it is a great country with some of the nicest people I have met in my travels.
I'm very new to laptops... my vaio fj is my first one in fact. I am going to japan to visit family in a couple of weeks and i was wondering if i'd be able to use my ac adapter for my laptop in japan. my mother informed me that i might not be able to because of a difference in something with the electrical outlets... if i will not be able to use the ac adapter as is, is there anything i can get that i'll be able to use my laptop while in japan? I'd like to just go with the battery alone but the battery life is around 2-3 hours. thanks in advance