MADDER: I Am the Culprit in That Case

Kurokawa (Yamamura Ryuta) turns himself in. Akane (Ioki Mao), unable to understand why Kurokawa, who she thought had fled, turned himself in so easily, is overcome with a sense of emptiness, in contrast to the relief and excitement around her at the arrest of the culprit. Meanwhile, Akane visits the Shinozaki family with Yohara (Mizuno Kyoshin) at the request of Shinozaki's (Yoshina Riru) father, Hirohiro (Kagaya Kei), who wants to talk to his daughter's classmates. However, while Hirohiro is crying over his daughter's sudden death, he also seems to be trying to extract some information from Akane and the others. Noticing this, Akane gets close to him, pretending to regret the death of her classmate, and asks to see Shinozaki's room. Then, she discovers some surprising data on Shinozaki's tablet...

The body of a classmate without a left arm was found on the rooftop. As the students panicked, Akane (Ioki Mao) found Kurokawa (Yamamura Ryuta) with a cold expression on his face on the other side of the crowd. In response to the incident, the students were forced to go home, but Akane went to the rooftop after the scene investigation was completed. Then, Eto (Higuchi Kohei) and others arrived and accused Akane of being the culprit. The motive was that the victim, who had recently become interested in Akane and was sniffing around her, had become a nuisance. However, Akane burst out laughing at such a naive idea. However, it seems that Kajitani (Takeda Rina) of the First Investigation Division also considered Akane to be one of the possible suspects, and Akane was questioned.

The Seiran Unification is to be carried out on a new date, and Akane (Ioki Mao), who wants to believe in people's conscience, slips a card into the belongings of the foolish geniuses. Meanwhile, Kurokawa (Yamamura Ryuta), who was cleaning up the principal's office, discovers a wiretap. Kurokawa instantly realizes the identity of the culprit and says something meaningful to Akane, who is enjoying a crime-like act. His words make Akane even more interested in Kurokawa.One day, Shinozaki (Yoshina Riru) brings up the story of a murderer who is making waves in the world, and provokes Eto (Higuchi Kohei) and the others, speaking as if she knows his identity.

The Unification of Seiran is suddenly canceled! Behind it all lies the motive of an analogue teacher who is fighting alone in rebellion against the school! Akane (Ioki Mao) motivates the foolish geniuses to move on to the next plan...

The culprit himself is working behind the scenes to solve the stone statue destruction case! With the assistance of Akane (Ioki Mao), who has grown impatient with the lack of progress in the search for the culprit, the truth is revealed! What is the secret hidden in the stone statue?

Nakano Akane (Mao Ioki), a genius high school student with a standard deviation of over 78, meets Kurokawa Yu (Ryuta Yamamura), a young man who is believed to be the perpetrator of a murder case, and causes a small incident at school, which eventually leads to a serial murder case that will shock Japan.