This is an interesting thread. Reading the questions and comments back and forth, I have something to share. From a marriage perspective, yes all reasonable considerations needs to be thought of before you commit anything, but very few marriage result from practical consideration in the beginning, there is something in us when we were made by our creator, to enable us to all of a sudden have a special feeling to one particular individual, this is a hint from our creator that this particular individual might be a good fit.
Yakitori met this girl on the airplane and starts to feel the crush on her, he obviously fell in love with her but she may not be in that mood yet, this is all very normal, I don't think Yakitori went too fast. Love is a passionate feeling, not a calculated move, well, at least Yakitori has passion to her, so he is looking for advice whether she may have the same feeling to him here on this board, by getting some cultural help.
Japanese woman are very subtle, way more subtler than American woman (like I could joke with my female landlord in the US "let's get married" but this perhaps will be considered rude in Japan), and she works in the airline, obviously she gets to meet many people from different country every week. An attractive sweet Japanese lady is not going to be someone only you feel the crush. So she is right here, saying you are free to have the feeling toward her but she may have her other considerations. If your crush is toward someone at your neighborhood, things are much easier. Now I am not saying it's not possible, it is just a little more complex.
My suggestion is don't smother your own feeling, you get nothing to hide, you have the crush to her then tell her, if she likes you internally and she thinks its time for her to commit to a man she will respond sooner or later. Relationship is never easy and straightforward, but rather than letting the unpredictability of the other part frustrates you, just to be true and honest to yourself, we don't have many years to be young, when we should be looking for and giving love despite other practical concerns, such as language and country difference.
Just some of my thoughts, may not be all right in your situation. Hope this can go well!