Hi! I just made this account to clarify some stuff about Kitaku since I am following this artist the first time I knew them by internet (I'm going to use this pronoun to refer to the artist since we cannot take anything for granted about them).
Let me explain.
Kitaku has three twitter acounts as far as I know: an artistic one, where they post their doujins and other yuri/Nijigasaki related stuff; a commercial one, where there's only information about the hetero hentai they make, and a personal one, when they post more yuri/Nijigasaki/idols related stuff and things they like/love/find cute. I think Kitaku is probably a female because in the personal account there are many posts of them showing the accesories, clothes, teddies, meals and other girly/cute items they have bought. I would say that those kind of things are not usually liked by males, or at least not to that extent. However, the evidence that most convinces me that Kitaku is a female are the following tweets:
Here they post an image of a female hand model she bought on Amazon, and then post another tweet saying: "If you bend your little finger slightly, you will get a sexy hand gesture": https://twitter.com/ktk_er18/status/1277247235206479876
Here Kitaku says something like "I became the camera girl of my dreams" referring to themselves: https://twitter.com/ktk_er18/status/1212192304133357569
In other tweets they identify with Yu in the sense of being a girl who is interested in collecting photos of pretty girls.
Buut, in any case, we cannot be sure about their true sex/gender since we don't have enough information about them that we can grasp from their twitter accounts. We just know that Kitaku likes Love Live series, cute/sexy girls, yuri stuff, little, fluffy and fancy items and the H genre (who wouldn't?)