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!