I was using google flight search to look for a one-way NRT-SFO in C randomly on some dates in May. There is a $500 fare difference if I search for the same flights on directly on UA.

When I click through the link in google to price it on UA.com, the fare is in foreign currency but it does give convert in USD to the lower price.

Intermittently, I'll get a message that says I need to have an valid address in Japan to buy the ticket and it reprices at the higher price.

Has anyone had success in purchasing a ticket from this approach?