Macs just bluffing, if he as sensitive to what those around him think about him as he claims to be, no-where is safe for him.
Games up mac, we know you love japan, we also know you need to vent sometimes and you do it here, no worries, have you ever seriously sat down and told your wife (japanese?) about how you feel?, i find it hard to believe that if your so seriously bothered by a percieved descrimination, you would marry a woman who if i remember correctly, youve said has been guilty of at least a minor insult in the descrimination regard (saying gaijin or something).
Basically if it was really a constant drain on your very soul, you probably wouldnt have been there aslong as you have and you would never have married a japanese woman, i know this, and so do you.
Dont let japan get you down, and instead of seeing everything as dark and miserable, concentrate more on what you lvoe about japan.
As for the japanese passport thing, i think they are just being polite, rather then insulting you as you percieve, they just dont want you to possibly face the embarrassment of being in the wrong line.
As a rule maybe hold your japanese passport in plain view in your hand when you join the line, to avoid that situation.
And in a country that is 90+% ethnic japanese, its a bit unfair to blame the japanese for associating the asian face with japan more then the westerner.
I dunno, im not a giant, not blonde and i dont have blue eyes so maybe im not such a shocking sight to face, but, the japanese arent trying to be impolite and offensive.
All i have is my meager experience for me to decide if japan is really descriminating or not, and for the most part, i have to say not.
The situation with my girlfriends uncle did prove to me that it does exist, but it isnt such a burden that i face it the momment i step outside the front door.