I'm a US resident planning on booking a RTW starting in Japan combined with a Japan round trip. The idea is to fly out to Japan on the round trip, use the RTW to return to the US via Europe, then do another trip to Japan in six months on the RTW, then use the return portion of the first ticket.

My question is whether UA will deny boarding on the first leg since I won't have a Japanese residency visa. I have already confirmed with the Japanese consulate that this itinerary is allowed.

I guess worst case is I bring a letter from the consulate with me to the airport?