In case it was only me that is confused about evisa to Vietnam: Flying on JAL LAX to NRT to HAN They absolutely would have stopped me from boarding to NRT according to two agents at the airport. Also I did end up getting the evisa when I landed in NRT but needed the 8 hour letter to get there.
Once I got to VN all they asked me for was my passport and the evisa from government that I printed up in NRT lounge. I did not need the form I filled out or the two passport photos I thought I still needed after getting the evisa. Not sure if that was my mistake, mistaken advice, or quirky immigration agent.