If you can't check-in your luggage in the morning, you could leave it in storage. Coin lockers are cheaper if your stuff will fit:

Coin Lockers:
http://www.narita-airport.jp/en/guid...svc_07.html#t1

Don't leave your luggage in a coin locker on the day before you fly - it will incur 2X the daily charge. (i.e. the locker charges per calendar day, not per 24hrs)

Left luggage services:
http://www.narita-airport.jp/en/guid...svc_06.html#t1

The luggage services charge per item ... so it's better to have one big suitcase than a collection of bags.