Originally Posted by
TOMFORD
I have an ICOCA card from my previous trip to Osaka and Kyoto, can I use that in Tokyo as well? Is all of the Tokyo metro accessible using the ICOCA card?
Yes. You should be able to use your ICOCA card on all JR as well as non-JR trains and buses (edit: in Tokyo). See here for more details on what exactly is covered and where:
http://www.japan-guide.com/e/e2359_003.html