Associate Professor Akira Takatsuki's Conjecture, Vol. 4 (manga)

The truth behind Mana, the -Miracle Girl of Okutama,- comes to light! Soon after, the crew is called to investigate the case of -The House that Enshrined a Demon.- There, they find not relics of an Oni, but rather a human skull with a gaping hole! All this and more, as Professor Takatsuki and Naoya-s hunt for the supernatural continues!