Associate Professor Akira Takatsuki's Conjecture, Vol. 2 (light novel) — Mikage Sawamura

It's no secret that Associate Professor Akira Takatsuki is a die-hard mystery fanatic, and with the help of human lie detector Naoya Fukamachi, he's determined to solve every case that hits his desk. First, a group of elementary schoolchildren claims to have contacted the spirit of their former classmate through the Kokkuri-san game, and it's been causing quite a stir. Then Naoya falls ill right around the time of the school festival, and his ability to discern lies…vanishes! And as if the timing couldn't be any worse, a well-known actress requests that they investigate ghost sightings on the set of an upcoming horror film. Lastly, stories of a young girl being worshipped as a living deity have been making the rounds, and it falls to the professor and Naoya to uncover the truth!