I think you’re probably better off getting a rechargeable JR/Subway IC card (called ICOCA in Kansai, or Suica in Tokyo) or Passmo card at airport when you arrive (all three cards work the same). Those IC cards are easy to use and work across the whole of Japan on all public transport, even some taxis too.
The subway ticket you mentioned doesn’t work on the JR train lines in Tokyo, so it’s possible you’ll end up having to buy extra JR tickets.
We have an article on all the various Tokyo tickets, but in my opinion they probably don’t save you much money (and might end up costing more!):
My standard advice is get the JR Suica/ICOCA or Passmo card.