I've made a couple more trips to Jpn since my last post but didn't do any tax-free shopping on those trips. So I'm still curious to find out what would happen if you put your tax-free CONSUMABLES in the checked bag and then you're forced to swing by the Customs Counter after check-in on your way to the gate. I certainly hope the customs officer will be satisfied with "It's in the suitcase I checked in already, but I promise you I have not opened the seal yet."
Folks, if you happen to go through the above scenario, please report back here!