Does anyone know this manga/anime?

I just vividly remember this manga and unsure if this is also an anime. Its been bothering me not being able to remember the title well enough for me to re read it again. There is a ghost been lurking on their school and there was this boy who only seem to see her. I forgot if the boy has a twin sister or not. The death of the ghost was like from pandemic of their village or so, and the principal or perhaps dean of the school is the boy's grandma and his grandma was like used to be friends with the ghost while she was still alive. He and the ghost also did fell in love with each other but thats all I could remember and want to know its full story again till Im satisfied. If anyone does know, I'd really appreciate it. (〜￣△￣)〜