Book Girl and the Famished Spirit (light novel)

Tohko Amano is a perfectly ordinary Book Girl-she loves stories so much that she devours them. But some stories are too intense even for the specialists. Mysterious coded messages start to appear hinting that a ghost is stalking the school, and what can Tohko do but try to defend the book club from it? She’s the president, even if she is a little . . . terrified.
But when the ghost turns out to be a real girl with two souls, hovering on the edge of life and death, light and darkness, love and hatred, the Book Girl’s skills-and those of Konoha, the trusty, level-headed Watson to her Sherlock Holmes-might be the only way to solve the mystery.