Muhyo & Roji's Bureau of Supernatural Investigation, Vol. 3: Into the Arcanum

Muhyo's friend Biko has a big problem. One of Biko's magic locks has been broken, and now something's escaped from the bottom level of a top-security prison for the evilest, most dangerous ghosts. It's up to Muhyo and Roji to restore order, but what will they do when their greatest fears are realized?