Before the investigation begins, Monokuma presents the students with the first Truth Bullet of the game: Monokuma File 1. As in previous installments, this piece of evidence acts as an autopsy report, with information that may prove useful later. After the students discuss, Kaede and Shuichi will be free to begin their investigation, starting with the scene of the crime.
Starting from the right of the room, examine the front bookcase. Shuichi will note that the books on top of the bookcase that Kaede arranged haven't been moved, giving you the Stacked Books Truth Bullet. Speak to Ryoma, standing in front of the bookcase, and the front double doors, then turn left. Speak to Kirumi and Shuichi. Shuichi reveals the mechanics of the moving bookcase, though it doesn't look like the perpetrator used the hidden door to escape, as the Card Reader Dust hasn't been moved. Examine the moving bookcase again to take a closer look at the sensor, revealing that it can be turned on and off using the Receiver on Shuichi. Speak to Miu and Tsumugi, on the far left of the room. Tsumugi points out that the Promotional Video BGM must have had a hand in driving the murderer's actions. Examine the rear sliding door next to Tsumugi. Finally, examine the back corner of the room to approach the body.
Near the body, examine the Bloody Shot Put Ball and the body itself for Rantaro's Belongings. After leaving the body, examine the Library Vent above the front bookcase. The investigation continues in the Game Room, which can be found on the other end of the hall.
Speak to Maki for Maki's Account of the events leading up to the incident. Then examine the sliding door at the back of the room to enter another area. Examine the video rack and poster bucket for some extra scenes, and the screen and the Sliding Door to continue the investigation. Then speak to Kaito, Himiko, and Gonta before exiting. Speak to Angie and Tenko in the hall on the way to the next destination, Classroom A.
Upon entering the room, Kaede and Shuichi explain their alibi in the Lookout Classroom, as well as the connection of the Classroom Vent to the Library. Speak to K1-B0 for K1-B0's Account, in which he explains that he was alone in his room during the time of the murder. Speak to Korekiyo for Korekiyo's Account, in which he notes some peculiar behavior from the other students in the moments leading up to the crime. Speak to Kokichi out in the hall, then return to the Library to question one of those students.
Return to the Library
Speak to Tsumugi for her explanation. After another scene, the students will receive the Front Entrance Photos, Rear Entrance Photos, and Hidden Door Photos. This concludes the investigation, so speak to Shuichi and then head to the back of the Courtyard, where Kaede can access the Shrine of Judgment. Speak to the students there, then examine the statue in the center of the area to proceed to the trial.