LIAR GAME roots of A #2(2010)

After being inspired by Professor Yukiya Okabe, fourth-year student Shinichi Akiyama has decided to pursue graduate studies to learn more about the human mind. While Akiyama is having a one-on-one consultation with the professor, a faculty member from another department, Mitsumasa Iwashita, interrupts the two. As Iwashita urgently requests to discuss an important matter with Okabe, Akiyama cuts his consultation short.

However, that does not stop Akiyama from eavesdropping on their conversation. He overhears that the science entrance examinations have been stolen, and one of his close friends, Kouichi Aratani, is accused of being responsible for this occurrence. Having known him since high school, Akiyama believes that his peer would never commit such an offense. With the guidance of his professor, Akiyama goes through every possible detail in this exceedingly intricate case.

(Source: MAL Rewrite)