After the body discovery, Monokuma arrives with Monokuma File 2. However, Shuichi notices that some important details are missing from the autopsy report this time. It is up to him to uncover the mystery behind this missing information. This investigation will be done with Kaito by his side, though whether or not his insight has value remains to be seen.
Speak to Gonta for Gonta's Account, in which he mentions that he didn't see Ryoma in the tank before the incident. Speak to Kokichi, Tsumugi, and Miu. The latter offers a Truth Bullet, Insect Meet and Greet, concerning the timeline of the previous night's events. Speak to Angie, Himiko, Kaito, Tenko, Keebo, and lastly Korekiyo, who leads Shuichi and Kaito backstage. Examine the rope and puddle. Shuichi then notices the Wet Staircase leading up to the tank. Examine the stage staircase and large water tank to leave the area. Examine the area near the water tank to approach it.
Near the water tank, examine the curtain, Ryoma's belongings, Ryoma's body, and bucket in front of the tank for Crammed Piranhas, as Angie notes that the piranhas seem to have miraculously multiplied. Inside the tank, examine the glass, Scratched Handcuffs, and Square Glass Pane. While the latter two items seem to have some relation to the case, it is unclear how just yet. To the left of the tank, examine the light panel and ladder. Examine the stage to approach it, then speak to Kirumi and examine the timer, Piranha Tank, and curtain to reveal the Marked Window Frame. After investigating everything, go to the next area of interest, the Ultimate Magician Lab located on the first floor of the school building.
Ultimate Magician Lab
Speak to Tsumugi and then Kokichi for Kokichi's Account, in which he details an encounter he had with Kirumi the night before, as well as the sighting of a girl in lingerie outside. Examine the large water tank to the left of the room, as this is the only item that has any relevance to the case. Shuichi will attempt to uncover the secret behind the Water Tank Trick, though he can only find a panel near the top of the tank that opens up. Still, he determines that this should be the secret behind the trick. Shuichi and Kaito can then head for their next destination, the Ultimate Tennis Pro Lab on the third floor.
Ultimate Tennis Pro Lab
Examine the door to the shower room to discover the room that really lies behind it. In this room, examine the closed window and Shuichi will discover that it opens up to overlook the pool. The Marked Window Frame Truth Bullet is updated here as Kaito notes that the frame of this window is marked in a similar way to the one in the Gym. Lastly, examine the Scratched Sink and the handcuffs on the wall to update the Scratched Handcuffs Truth Bullet. Shuichi concludes that these clues are all related, but he can exit the room to find one more clue via Kaito; conclude the investigation here by examining the tennis net, as the two will notice that the Tennis Net Cable has been separated from the net. Next, go to Maki's lab.
Outside Maki's lab, speak to Kirumi for the Witnessing Ryoma Truth Bullets, as Gonta and Miu are noted to be the last students to have seen Ryoma alive. Speak to Maki for the Maki Alone Truth Bullet; apparently Maki has been standing guard outside her lab the whole time, but Kaito doesn't believe she has anything to do with the murder, so the investigation here is over. Go to the Courtyard to visit the next destination.
Examine the school building window, now known to connect to Ryoma's lab. In the pool itself, examine the Black Piece of Fabric; while it may look like trash, it wasn't in the pool before, making it potentially significant. Examine the inner tube, Storage Room Door, gym window, and School Rules. After examining the latter, Monokuma arrives to inform Shuichi and Kaito that no one was swimming in the pool at night, but this only pertains to those who were alive. Then also investigate the pool’s storage closet. You should find an electric air pump . Exit the area after investigating all of the above and head to Ryoma's dorm.
Ryoma Hoshi's Room
Upon entering the room, Shuichi and Kaito search for the motive video to no avail, though Shuichi notes that this could be a clue in itself if the video really was a motive for the murder. After some more discussion, the investigation comes to an end. Head to the Shrine of Judgment to proceed with the trial.