I. Kanon's escape
Things we know:
- In EP2, Kinzo was shown being very friendly to Kanon.
- In EP2, a point was made of concealing Kanon's real name.
- In EP4, everyone in the dining room acknowledged "Kinzo's" existence.
- In EP4, Beato was unable to deny the possibility that someone had inherited Kinzo's name.
- In EP6, we found out that Kinzo treated Kanon almost like a son.
- In EP6, Kanon's real name was supposedly revealed... anticlimactically, and only in front of one person.
- Erika told Battler to exclude "Kinzo" from the location check without actually verifying that "Kinzo" didn't exist on the EP6 game board.
Kanon is Kinzo's son, and rightfully inherited his name at birth. He was never in the cousins' room in the first place, and Erika didn't realize it because she'd been cleverly lured into excluding him from her checks.
II. The person limit
We were told that
Hideyoshi, George, Shannon, Kumasawa, and Nanjo were in the next room over, and "everyone else" was in the cousins' room. Unlike Kinzo, Erika herself was not excluded from the location check.
That means her existence in the hallway is impossible. The only way she could have left the guesthouse is by going out the window in the next room over. And no one existed in that room except the five people who were named!
Erika is the culprit of EP6. And in EP5, we were told that
the culprit must be someone who was introduced in the early part of the story. Putting that together with her apparent nonexistence,
she must be an entity like Beatrice: a "detective's illusion" to match the "witch's illusion". So when she takes actions on the game board, it's actually an illusionary facade over the actions of the real culprit.
That culprit was Shannon, who was in the next room over.
III. The meeting in the guest room
Next we need to figure out the reasons for the pieces' actions so that the plot doesn't descend into a mess of meta-gaming. Why did Kanon go to "rescue" Battler in the first place, and why did Battler prepare a dangerous scalding water trap for Erika instead of just walking out of the guest room?
More things we know:
- Battler thought he was participating in an innocent farce mystery.
- Battler had no way of knowing that Erika had duct taped the outside of the door.
- When Erika entered, Battler was hiding somewhere in the room.
- Excluding one place, Battler was not in the room.
- According to Erika, she searched the room except for one place, which was the closet.
- Battler left while Erika was in the bathroom.
- Kanon's rescue of Battler may or may not have been intentional.
The key to the whole thing is that Piece-Erika isn't the detective, she's a fantasy piece masking the culprit. Her perspective isn't reliable, and we can't trust even a single thing she sees or does unless it's backed up by red truth. Red,
not blue. That was the second critical error that Meta-Erika made: believing that her theories corresponded to things her piece was actually doing.
Shannon is a knowing participant in the farce mystery. She left Battler alive in the guest room for a very simple reason: she needed him to continue the farce in order to disguise her real murders.
After leaving the guest house, Shannon met up with Kanon, and they went to the mansion together to discuss their next moves with Battler.
Shannon opened the door for Kanon to let him in, and then entered and immediately closed and locked the door herself, not leaving any time for someone to slip out.
At the moment they entered,
Battler wasn't on the bed. He was definitely hiding somewhere in the room. But he came out of hiding when he realized who it was, so Shannon didn't need to search the room at all.
The one place Battler (and Kanon) could exist that was excluded by the red wasn't the closet as Meta-Erika believed, but the center of the room, where everyone was standing and talking to each other.
IV. Kanon's murder
When they were finished, Shannon went into the bathroom for a moment, perhaps to get a gun she had hidden there earlier. The trap that Meta-Erika saw existed only in the fantasy world of her piece's perspective. Battler left to take care of business, and Kanon reset the chain lock behind him. When Shannon came out,
she made sure that Battler was gone, and then shot Kanon dead and stuffed his corpse in the closet. Because he was dead, he no longer counted as "existing" in the room.