Now wait a minute, the answer to the question about if you were born 100 years earlier is disturbing me
Tsukasa answered about WWI and the earthquake which were around the early 1920s
If 1920 - 16 (Tsukasa's age probably) = 1904 then add 100, you will get 2004, Tsukasa's year of birth probably around 2001-2004
But then if she really was born on one of those years, what about the hint she always mentioned when looking at historical sites?
Yeah... It conflicts with all the other answers she's given in the Q&As and what you said just here. I'm not really sure why she said that when it's all but obvious she's been living for over a thousand years, but maybe it was an attempt to preserve the illusion that she's the age that she says she is, even though every other answer points to her being much, much older, like the one about the first movie she saw being literally considered one of the first movies to ever exist, if not the first, or a book from her childhood, or her hometown, or... I could go on.
To be honest, I like the explanation by
@DeProgrammer - it's probably ambiguous Japanese translation, and that it was probably meant to refer to the time period 100 years before current era.