Maybe some of you actually know of good titles in this type. Girl in question is 12, but is more into stuff for somewhat older girls, so I would not recommend her very safe, kid stuff, as that will not interest her. Also, no faggotry please, the world is pushing that shit on all of us all the time, so it's best to not open another venue for it. Needs to be available in English, and the more obscure stuff I might not be able to get for her, I assume it is at least somewhat limited what books I can get here.
She is also into horror movies, if that helps.
Thank you to any of you fine gentlemen for any recommendations.
I just want to praise everyone in this thread for giving thoughtful replies. "looking romance manga for a 12 year old girl," is so ripe for trolling. Only more so if OP had said "for my little sister."
Didn't read, only watched, but: The Ice Guy and His Cool Female Colleague is a fun one. Office romance with some supernatural window dressing. Very clean, just two adults figuring out their own feelings with some light comedy thrown in.