What to do during my overnight layover in NRT

Hello,

I am arriving to Narita at 8:30pm on a Friday evening and my next flight wouldn't leave until 11:45am next morning from Narita. I have already got my temporary visa and would like to explore Tokyo while I have a chance. Any insight on what I can do? Is there a place I can store my luggage while I explore the city?

Thanks ahead.

You can store your luggage in coin lockers at the airport.

There are lockers and a baggage check service in T1 and T2 at Narita.
http://www.narita-airport.jp/en/bf/service/info08.html

If you go into Tokyo (or anywhere) late, be aware that most of the trains that got you into town along with the subways will shut down at 11pm to midnight, leaving you in town wherever you got off. Almost everything except some bars and nightclubs will be closed so what do you plan to do? The first N'EX train back to the airport starts at 6:18 am from Tokyo Station, but for most of the night you will be stuck in town with no transportation other than taxis.