You Will Hear the Voice of the Dead

You Will Hear the Voice of the Dead (死人の声を聞くがよい, Shibito no Koe o Kiku ga Yoi) is a manga written and illustrated by Hiyodori Sachiko.

Plot
Jun Kishida is a sickly high school student who can see dead people. One person in particular is following him around: his childhood friend Ryoko Hayakawa. Even after he uncovered the truth behind Hayakawa's death, she stayed by his side. As he and his classmates get into even more strange and mortally dangerous situations, Hayakawa's spirit quietly aids him.