Being a non-traditional, Tatsume is the owner of a maid cafe in Akihabara where Narumi has one of her practices (that she requested for). She was also graduated as the first of her class from the Maid's University. She gives a particular lesson to Narumi about what it means to be a maid... Source: Chapter 2
NoHeart Note: He is a cross-dressed maid as Narumi and also Matome`s father. He also knows the "secret" of Narumi.