The manga girl might be able to see ghosts because of a family inheritance or a pact she made unknowingly. It could also be that she was in a near-death experience that gave her this power. Another possibility is that she was chosen by some higher supernatural force for a special mission.
It could be full of spooky and mysterious adventures. Maybe she uses her ability to help solve ghost-related problems or has to deal with scary situations.
Well, you might want to check out 'The Ghostly Girl's Vision'. In this manga, the girl not only can see ghosts but also has to deal with the challenges and mysteries they bring. Another one could be 'Phantom Sight' where the girl's ability leads her into a world of hidden spirits and secrets.
Manga is a form of creative storytelling. Seeing ghosts is a supernatural concept that doesn't come true through reading manga. It's all made up for the sake of the story.