Watatsuki no Yorihime
綿月依姫, Yorihime Watatsuki
A lunarian who is at least over 1000 years old who easily absorbs knowledge. She and her sister are currently in charge of the Lunar Defense Corps. She was formerly a student of Eirin a medicine genius from the moon who is now an exile and now staying with Kaguya on Earth in Gensoukyou.