Well, you wait for the next chapter or for a completely different series Or you could start reading on a different genre. There were a lot of mangas out there that somehow resembles shoujo based themes.
Hi, Chaos. Enjoying summer vacations? And oh, what is this new avatar you have? I can't tell from the perspective. I'd guess, but my perverted mind might make the wrong assumption.
She only appears in the Tsukihime anime in a form of a black cat.
The only major appearance she had is from the Visual Novel Kagetsu Tohya, which is the sequel to Tsukihime.
Or you could read this link and search for her name. Here