Agree with you there's no way shes Japanese... she definitely wouldn't say "Asian"... in fact, having taken 6 semesters of Japanese in college and lived there for 10 months, I'm not even 100% certain that there is a Japanese word for Asian like an asian person.. ajia-jin?

ANyway, here's my guess: Filipino

1.Her Asia travel: HK, and vietnam are the two closest major destinations to the Philippines . Also, no Japan trips yet (despite a clear fondness for Japanese food), which makes me think shes not as close to japan.

2.She got her bachelors degree in Australia. Taiwan has a ton of higher education. The Philippines, not so much. Obviously, its not impossible for a taiwanese to study abroad all four years, but it seems like something more likely to happen

3.The following quote fits with Filipino two ways "Egg pudding with durian sauce: The egg pudding is similar to flan pudding". The Philippines is one of those countries thats "into" durian, and she assumes that flan would be a familiar basis of comparison.

4.She seems to enjoy heavier food than the typical asian fare. Flour based pastries (like cupcakes) beef pork even a steak. (of course, 4 yuears in australia and a lot of travelilng could be responsible for that)

5.In addition to being a japanese name, miki is a type of Filipino noodle.

See i would never be able to have all this fun speculating if she spoiled the mystery from the get go.