You must take care of certain things after landing in Japan.
Exchange money in the airport
+ You may not see too many forex around
Check the weather
+ If it is cold or during winter, please wear proper clothes in the airport itself
Use public transportation
+ Take a limousine bus or train from airport to the nearest station or place where you will live
+ DO NOT take a TAXI - It is very expensive
After reaching your place of stay
+ Many restaurants are open late in the night - Get something to eat
+ Convenience stores (or mini super market) are available almost everywhere these days and they are 24H Open.
+ You can get bread or some ready to eat food there
+ Before going to bed, ensure you set alarm or wake up on time to go to customer office next day