House

By coincidence, I am taking the 5pm CA flight to NRT today!

I think you should be OK, as long as the SQ flight is on time.

Your arrival and departure flights are from the same terminal, Terminal 2, at PVG. Try to get SQ to tag your luggage (if you have anything checked) all the way to NRT.

When you get into the terminal, you have a long walk from the gates SQ use to immigration. When you get to the stairs down into the immigration hall, do not take them. Instead walk past them. Just after that, on the left hand side, are some International Connections desks. These are usually available for connections on Star Alliance airlines, but are not always staffed.

If the connections desks are staffed, then they should be able to give you your CA boarding pass and verify your SQ baggage tag numbers. You then go through a security check and upstairs into the international gate area. If there are no Air China staff on duty, they can call for someone to come and process you. This takes a little longer but you should still have time. It is helpful to have a printout of your itinerary or at least the eticket number, in case of queries.

If the desks are not staffed at all, or if you have luggage that is only tagged to PVG, then you need to go through immigration and customs (should be fast at that time of day) and then upstairs to check-in. Note that Air China have separate domestic and international check-in areas, so keep an eye on the signs. Also, note that international check-in for Air China at this time of day can be a zoo. If you are running close to 1 hour to departure, go to the Business of First Class desks and ask either them, or the supervisor sitting next to them, to check you in.

Once you are checked in, it is easy. Through security and getting to your gate should take 15 minutes or less.