The body of a classmate missing her left arm was found on the rooftop. While the other students panicked, Akane saw Kurokawa standing behind the crowd with a cold expression on his face. Following the incident, the students are forced to leave school, but Akane goes to the rooftop where the investigation has been completed. Eto and the others arrive and accuse Akane of being the culprit. Apparently, the victim had recently become interested in Akane and had been snooping around her, so that was their motive. However, Akane laughs at their childish reasoning. Kajiya of the First Investigation Division also considers Akane a suspect and questions her.

Seiran Unified is being held on a different day, and Akane, wanting to believe in the good conscience of people, slips a card into the belongings of the foolish geniuses. Meanwhile, while cleaning up the principal’s office, Kurokawa discovers a listening device. He instantly realizes who the culprit is and makes a meaningful remark to Akane, who seems to be enjoying her criminal act. This makes Akane even more interested in Kurokawa. One day, Shinozaki brings up the topic of a serial killer causing a stir in the media, which provokes Eto and the others, as if Shinozaki knows the killer’s true identity. Akane also becomes interested in the topic, but…

The “Seiran Unified,” a school test that is directly linked to the school social hierarchy and is said to have a major impact on students’ future career paths, is suddenly canceled. Determined to find the culprit who forced the cancellation, Eto is set on bringing them to justice. With her classmate in her sights, Akane prepares her next scheme while eavesdropping on the principal’s office. There, her homeroom teacher, Kadokura, and the assistant homeroom teacher, Sasaki, hint that the cancellation was due to a leak in the exam information. Kadokura asserts that Minowa, the classical literature teacher, must be the culprit. Unbeknownst to her, Miyauchi was eavesdropping on this conversation from behind the door.