Let's look back at the first murder. It was late last night. The culprit was in the empty room on the 4th floor. The culprit was preparing the seance murder they had planned. To use the floorboard as a seesaw, they had to cut the crosspiece supporting it. The plan was to make the same preparations for all three empty rooms. This would divert suspicion away from the culprit and to whoever picked a room. To cut the crosspieces, they needed a saw. I imagine they got one from the warehouse. They were planning to cut the crosspieces in all three rooms. However, when the culprit was working on the middle room, the unexpected happened...
Angie walked into that room and saw the culprit making their preparations. She needed some fire for the ritual, and had gone to the room for a candle. At that point, the culprit had not finished the setup and was just cutting crosspieces. Angie might not have concluded that it was tied to some kind of murder plan. But now that Angie had seen it, the culprit couldn't use the seesaw trick. Any other person might have just given up. But not our culprit. The culprit took the floorboard they loosened and struck the unsuspecting Angie in the head. The culprit did not want to give up on their plan and had to improvise.
They wrapped duct tape around Angie's injury to stop the bleeding. Then they picked up her unconscious body and carried her to her research lab. While she was unconscious, the culprit hurried to tie up this loose end. But because they were in a hurry, they made a crucial oversight. They didn't notice the duct tape had peeled off, and was under Angie's body. Without that evidence, we may never have figured out the culprit's trick.
Carrying the supplies they needed, the culprit returned to the Ultimate Art Lab...locked the front door from inside...and took out the katana they brought from their own lab. They then stabbed Angie in the back of the neck, finally killing her.
Then, to further confuse us, the culprit attempted to make a locked-room mystery. First, they used the rope from the warehouse and hung four effigies upside-down. There were two reasons for this. To overwhelm the room with an occult atmosphere... And the other was the key to locking the room. The culprit stuck the katana into Kaede's effigy near the rear entrance...and spun the effigy around to twist up the rope.
After enough turns, the culprit let go and headed for the rear door. Once released, the effigy began spinning, and the gold leaf katana with it. The handle of the katana then hit the sliding lock, locking the door. A difficult trick, but remember that the lock was so loose it moved at the slightest touch. The culprit also would have had the opportunity to attempt it many times. Once complete, the door was locked, but the duct tape was left behind. Perhaps the culprit noticed it, but by that point it was too late. The room was sealed. There was no way for them to get back inside.
Then, this morning, we opened up the room and discovered Angie's body... But the culprit wasn't finished. They wanted one more murder. To do that, they manipulated us into performing the seance!
Of the three empty rooms, the middle one was chosen for the seance. I was invited by Kokichi to take Keebo's place in the seance. Tenko volunteered to be the medium. But...she never imagined it would get her killed. To perform the seance, the culprit claimed they needed something for Tenko... A small stone that Himiko had brought from the courtyard. Tenko, at the culprit's request, bowed her head until it was touching the stone. That position was instrumental in making sure the murder went as planned.
Next, Kokichi and I placed the iron cage over Tenko, in the middle of the magic circle. The culprit then volunteered to drape the white cloth over the iron cage. We didn't realize it at the time, but that was a deliberate decision by the culprit. They needed to set up the murder weapon that was used to kill Tenko. While they were covering the cage with the cloth, they secretly placed the sickle. Finally, the four of us placed the wooden statue on top of the cage. The culprit used the weight of the statue to keep the murder weapon in place.
After the preparations were complete, we began the seance. In complete darkness, we each stood in one corner and sang "The Caged Child" song. When the song finished, the soul of the dead was supposed to enter the medium...but our culprit had another plan - to commit a murder in the darkness.
Right after we started singing, the culprit began making their way toward Tenko. It would have been quite difficult to do in total darkness, but our culprit had a guide. They used the lines of the magic circle drawn with salt. The culprit felt for the salt and used it to guide them along. And when the culprit reached the center of the circle...they found the floorboard that had its crosspiece cut off the night before...
Then lifted up their foot and stomped down hard on the floorboard! The floorboard lifted up like a seesaw... ...and pushed Tenko's body up toward the ceiling of the cage. Tenko was stabbed in the back of the neck by the sickle on top of the cage. She was killed right before our eyes and we didn't even see it! After committing the crime, the culprit followed the salt back to their corner... ...finished the ritual, and had us light the candles. We followed the culprit's directions and removed the equipment used for the seance...
...and discovered Tenko's body. And while we were all focused on the body, the culprit picked up the sickle... ...and dropped it under the floor through the hole in the corner of the room. Ironically...the final step of the murder was unwittingly carried out by us. The culprit had planned the murder so that we would unintentionally destroy some evidence. That evidence was the magic circle that the culprit used to navigate in the dark. However, the culprit didn't know that Keebo had taken a picture. He really saved us. Without that, we wouldn't know what changes were made to the circle. But now we know for certain. And we know the culprit drew the magic circle...
Korekiyo Shinguji, the Ultimate Anthropologist! You're the culprit behind these murders!