The main character was a boy who could see spirits, which he eventually got used to seeing them around him. Apparently, his grandmother used to teach him how to exorcise spirits, but his memory was wiped at some point after that.
Anyhow, their family was supposedly responsible for protecting these cracks in the ground which led to the spirit world, and after his grandma died, he had to protect it instead. Oh, but because he didn't remember any spells, the protectors of the other cracks into the spirit world (at other places) came to his house to hold a meeting of some sort.
In the manga, there's also a pair of siblings who used weasels to fight or something..., or maybe those were their spirit animals... I don't quite remember.
Does anyone know the name of this manga? I'd greatly appreciate it if anyone does :)