There are 3 major Electric Appliances store in Japan: Yamada Denki, Bic Camera and Yodobashi Camera. Most of their stores are large and located near the station so it is very easy to locate them. All of the stores give points when you buy things from them, and you can you these points when you come back and buy some other things.
The links will show you the location of each stores in the Tokyo area.
1)Yamada Denki – http://yamada-taxfree.com/en/
2)Bic Camera (English) – https://www.biccamera.com/bc/c/global/transer/en_index.jsp
3) Yodobashi Camera – https://www.yodobashi.com/ec/store/list/en/