Shibito No Koe Wo Kiku Ga Yoi

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 Hayakawas death, she stayed by his side. As he and his classmates get into even more strange and mortally dangerous situations, Hayakawas spirit quietly aids him. Volume 4 contains the oneshot The Mysterious Tale of Yumi-chan