Chinese or Japanese Teapot

Hello experts - I have a tiny blue and white porcelain teapot from my great-great grandmother that had a note in it identifying it as a "Chinese teapot 1670", but when I researched the kyusu style, it would appear to be Japanese. Can anyone identify the written characters on the teapot and what they might say? Also interested in establishing its date of origin, if possible. (All pictures are apparently too large to load, but they are under the MaxxBandit profile)