Do we need to clear immigration/customs in Narita to have Narita count as a transit point?

Plan is SEA/LAX/PVG arriving 20:00 6th December. Then return PVG/NRT/SEA 21:00 10th December. I don't suspect the Chinese immigration care about what happens after leaving China but wondering about this. The other routing is the reverse - SEA/NRT/PVG and PVG/LAX/SEA. For this do I just show flight itinerary showing the inbound from NRT and outbound to SEA inclusive of starting/ending point of SEA?

I hope this is clear. We went through the process in PVG for a connection to HKT (Phuket) last month and it worked great, albeit very slowly. One agent working the Visa line and it took at least 5 minutes a person - one at a time, no couples appeared to be the MO. Our passports are US and Canadian.