I'll be traveling to Japan in January 2010, and then onto Singapore and Malasia, and finally returning home from Bangkok. My flight to SIN departs from NRT (on NW) and my journey home involves connecting at NRT (both flights NW, about one hour layover). I know there are lockers and baggage storage facilities in both arrivals and departure areas, but presumably those wouldn't be easily accessed during my short layover. Are lockers available that could be accessed airside during my layover?

I'll be traveling carry-on only (so no need to check a bag at this point), but wanted to avoid taking my coat and some heaver clothing items with me from chilly Japan to balmy Singapore.