Did you know they have shower rooms and day rooms at Narita airport for rent? The shower cubicle as they call it is available for rent. The cost is 500 yen per half an hour, not too bad considering you get to use their towel, soap, shampoo, conditioner and hair dryer! The day room which comes with bed and shower is only 1000 yen (single) per hour and depending on the size, costs half the price every extra hour. Not a bad deal especially if you don't want to smell like major B.O. and there are some out there who need it more than others...especially those who smell like chicken soup >_>; Check it out! Here's the link.
Happy (B.O. free) travels!