[splashpot]

Things that suggest the waitress may have met Hiro 6 months ago:

- She got the Japanese book for her birthday 6 months ago.
- When asked how she knows they're tourists, she abruptly says "just a guess" and changes the subject.
- She knew how to say "You're sweet" in Japanese even though it isn't in the book.
- She liked the way his cheeks wobble when he concentrates. When would she have seen him do that?

So assuming Hiro doesn't save her life and we don't enter an alternate timeline, why doesn't he save her? Maybe, in those 6 months, he realizes that doing so would create some sort of time paradox (if she doesn't die, Hiro doesn't go back in time to save her).

And why does she pretend not to recognize him? Does Hiro tell her about his power and instruct her to act as if they don't know each other? If so, does he tell her she is going to die? Even if all that is explained, why is Hiro not in the birthday picture until after he goes back in time? If all that happened 6 months ago, he would have been in the picture the whole time.