At the airport check-in desk ask for a seat next to the emergency exit because your legs, I don't know, must be longer than those of the Japanese or something. The check-in clerk will instantly realise that this is true, because all Japanese know Westerners have longer legs; it is common knowledge for them! Thanks to the vindicated smugness of the clerk a seat next to the emergency exit is almost guaranteed.
Non-smokers may want a particular seat in a restaurant as far removed from the smoking section, which is more often than not an open area. Point out how sensitive your eyes are. The maitre d' will see this as Truth and to show how aware he is of your genealogical differences he will happily comply.
Claim ignorance when asked if it is true that Westerners can hold their alcohol better than the Japanese* and be assured an evening of free drinks from the curious eager to test this hypothesis.
Japan has a rich vein of racial stereotypes the gamesman can tap for fun and profit. We are all equal but foreigners are less equal than others.
* It is.