Amazing news I just found out! The wonderful Three Lights, a repository for high quality Sailor Moon scans, has HQ scans of the ultra-rare calendar that Naoko Takeuchi and her husband Yoshihiro Togashi (creator of Hunter x Hunter among other series) made in 1999 to commemorate their wedding.
Artist: Madoka Oomori of the circle Pale Lilac (she was the former assistant of Naoko Takeuchi, hence why their styles are so similar and why her doujinshi can be considered semi-official!)