Glad you had fun!
If you thought now was hot, you just missed out on the late-summer heat wave due in a few weeks, so consider yourself lucky.
You can also now use ATMs at 7-11 to withdraw money from either a debit card or cash advance credit card. Menus are available in English (and some other languages), and fees are about $2-3 per transaction (plus any additional foreign fees your bank/cc might charge).
If you're flying into Narita airport and staying in Tokyo (or Kanto area), consider the N'EX+Suica combo. For ¥3500 you get a one-way ride on Narita Express (N'EX) to Tokyo station plus a Suica card (same as Pasmo) pre-loaded with ¥2000. If you plan on traveling beyond Tokyo, skip Suica/Pasmo and get a JR pass instead.