If you are the only courier for your courier company onboard, you need to carry an airway bill of lading while onboard. You do not need to carry any bags for the courier company since they are carried in the cargo area. You then need to wait at the customs area at your arrival city until a courier rep arrives and the bags clear customs. Sometimes, that takes awhile. Sometimes, there is more than one courier for the same company, and only one needs to go through customs at an interim stop (NRT), and then each goes on to a different city (SIN, HKG, MNL, etc.). I have never been required to carry a bill of lading on my return flights to the US, but you still need to be onboard or you get fined your deposit and you need to buy your own return ticket if you miss the flight. Usually, you can only take enough baggage of your own to carry onboard the plane, but sometimes the deal allows you to check baggage. The airfares are a very good deal, but in the past few years the companies have cut down the number of flights and the destination cities.