I read somewhere (can't google now) that the protagonist of Sora wo Kakeru Yodaka only has 200 days to retrieve her body, else the change is permanent.
I re-read the first chapters (thanks the author for the furigana), and there is some character saying that in 200 days all the cells in your body are replaced, so you are entirely another person after that time.
But where is that comment linked to the body change, I could not find.
