She's intentionally upside down. The rest of the picture is upright that way, if I rotate it like that then everything else looks kinda weird (the pillars, the arc in the bg, etc). She isn't from anything (I think), I got the pic from an artist on Pixiv named Fujihara (藤原) and I named the character Tomo.
Removed the white on the left, couldn't see it at first since I have flux installed and it is night now xD :

I think I'm going to "test" this one for a while to see if I like it enough to keep it for a longer time.
And Havoc, I've pondered over what to add to my Hitagi sig when I first made it. It looked too empty to me, after many hours I still had no idea and thus I left it like that. But fear not, Hitagi will come back.... someday.