Begin by examining Toko, then the hammer on the floor. Sakura mentions Celeste was attacked with Justice Hammer 1 and Hifumi was hit by Justice Hammer 2, so what happened to Justice Hammer 3? It's time to break the bad news to them, but out in the hall, Celeste has some bad news of her own. After some scenes, head to the art room. Here, examine the door to the repository. Unfortunately, it appears to be locked. Enter and exit the rec room and do the same with a classroom before returning to the art room and examining the door to the repository again.
Art Room and Equipment Room
Once inside, examine the hammers on the wall. The hammers are similar in design to the Justice Hammers, and many of them appear to be covered in a chalky substance - all except one, which happens to be wet? Could it have been washed, and why? This discovery earns you the Spotless Hammer Truth Bullet. Examine Hifumi for the Truth Bullet Hifumi's Glasses; Hifumi's glasses, covered in blood when his body was found in the nurse's office, are now mysteriously clean. Examine Kiyotaka for the Blue Tarp Bullet. Could this have been used to move his body? Finally, examine the dolly for the Repository Dolly Bullet; Makoto recalls seeing the dolly in the equipment room when he first discovered Kiyotaka's body, but the dolly has now been moved here, getting some blood on a wheel in the process.
Speak to Aoi to find out that the repository has been locked since the search began. Also make sure to speak to Byakuya and Sakura (answering "Yes" to her question) before leaving. Attempting to exit after speaking to Aoi will earn you the Repository Door Bullet. The door can only be locked from the inside, which would mean someone involved with the crime had locked it before the search for Robo Justice even began.
Return to the equipment room. Examine the hammer on the floor, then the bloodstain for the Equipment Room Bloodstain Bullet. It appears to have tire marks in it, which would indicate that the dolly in the repository really was used to move Kiyotaka's body. Examine the tarps, then speak to Toko/Genocide Jill. Exit to the first floor, then head to the nurse's office.
Speak to Celeste for her testimony, received as a Bullet in the form of Celeste's Account. Her story matches up with Aoi's; they had left the nurse's office for only a few minutes, and when they returned, Hifumi's body was gone. Examine the hammer, just as the group had left it when they first discovered Hifumi. Examine the refrigerator to the right, containing blood packs. Examine the trash can to the left to find a Glasses Cleaning Cloth which is, coincidentally, covered in blood.
Exit the room. At some point, if he hasn't already, Byakuya will present you with Yasuhiro's Message, asking Makoto to recall the writer of the incriminating note. It seems to be evidence that works against Yasuhiro, but Byakuya hints that there's another reason the note is interesting. Continue to Yasuhiro's room to investigate further.
Yasuhiro's Room and Pool
Examine the boxes in the center of the room to find Robo Justice Blueprints, as well as materials needed to make the Robo Justice suit. However, there's something off about the handwriting. Exit the room to find Aoi. After the conversation, you should find yourself in the pool area. Examine the group of students across the pool to get a closer look, then speak to Kyoko for the Robo Justice Costume Bullet. Kyoko has at last found Robo Justice, and in the process has found that it really is Yasuhiro inside the costume. However, Yasuhiro has trouble getting the costume off, requiring the help of his fellow students, and upon testing its size, Aoi has trouble even putting it on. Afterward, speak to Yasuhiro for Yasuhiro's Account. He doesn't recall attacking Celeste, Hifumi, or Kiyotaka, and in fact claims that he had been sleeping the whole time. He also mentions a strange note. Back out in the hall, head back to the repository with Kyoko.
Speak to Kyoko for the Broken Wristwatch Bullet. Kiyotaka's wristwatch has been broken, presumably when he was attacked, putting his death at approximately just after six o'clock. Kyoko also notices something clenched in Kiyotaka's hand. Makoto pries it out to find Kiyotaka's Scrap of Paper, but that's all it is - a blank piece of paper. Still, Kyoko seems to think it holds some importance. Next, examine Hifumi. Afterward, speak to Kyoko again. She found a note that Hifumi hid away, describing a meeting that may lead to escape. While the contents of the note are intriguing, Kyoko argues that the missing piece of paper that had been torn away is the most interesting thing about the note. This discovery earns you the Truth Bullet The Note Hifumi Had. Finally, Kyoko mentions that the e-Handbook may come into play somehow, though it doesn't seem relevant yet.
With all evidence now collected, proceed to the courtroom as usual for the trial.