since she is someone from Japan originally, how tf does none of the world leaders not realize it? She seems to be from a normal family, so there should be proper birth records.
How come none of the countries found any record of her?
It's hard to believe they weren't suspicious of her claims of being someone from another world.
After all, it's more plausible to assume that she might have just found undiscovered animals/resources somewhere on earth. They would have eliminated that possibility before they reached the conclusion that she was from a different world. Or at least, even if they were keeping their options open, they would still do more investigation than this.