Do you have priority pass? If you do i think you're able to access 9 hours capsule hotel at Narita for free. Another good option is to just hop on the Yamanote line and you can nap on the train for as long as you want without any bother (it travels in a circle).
Don't do it in places like McD or Starbucks. I've been kicked out of both for early morning napping even though I bought something (thought it would be fine since I saw Japanese youngsters doing the same thing).