Blue eyes, blonde hair, tall and narrow nose, distinct caucasian eye shape and eyelid folds?
If she were even the great grandchild of an mixed race conception a hundred years ago, it's highly unlikely that anyone would have that kind of hereditary consistency of features.
The only way I'd believe it is if they told me that her ancestors came to China as Protestant missionaries in the mid-1800's, had children, who then migrated to Hawaii in their lifetimes, had kids, and then for the next hundred+ years only reproduced with Caucasians.
This is 50 years of inter-racial mingling: