[Oliver]

Originally Posted by Renall

I like you. You have a lot of new ideas.

They're rarely complete ideas in any fashion though. This one definitely isn't complete and I was quite sleepy when I wrote it so it came out a bit more jumbled than it should have.

You see, I'm assuming certain things globally about the entirety of the text:

• The narration minimizes the amount of explicit lying and avoids it entirely if at all possible, but having said one lie, will stick to it for the duration of the episode. So, having said one lie in Ep1 about Krauss and Natsuhi distrusting the one-winged servants, it keeps at it and quietly forgets about it after the episode is over.
• When it does lie, it prefers lying at points where it would allow to indirectly paint someone who is innocent as guilty or an accomplice, aiming to eventually prove them innocent later in the text (usually by killing them in a fashion that leaves them dead beyond reasonable doubt) It avoids explicitly lying to us about someone who is actually guilty being innocent - it misdirects instead. Anything else would be cheap.
• While all the characters are involved in planning something shady, or at least, complicatedly manipulative, and lying to other characters, much less of them actually murder anyone than we normally think.
• Episodes are in an indirect way paired, i.e. 1=5, 2=6, 3=7, 4=8. For example, the most glaringly obvious (and impossible) culprit in Ep1 (Natsuhi, who has the only visible gun and is implicated strongly in the matter of Kinzo's death since Kinzo is supposed to be thought by the reader as alive at this moment) is completely exonerated from any murders in Ep5 in the trial, -- to us, if not to Lambdadelta -- despite being even the more obvious culprit than the first time around. A Chiru episode destroys the wrong solutions from the corresponding episode in the first quad and hints once again at the real ones, they're to confirm the theory you are supposed to form from 1-4, and new mysteries are there mostly for further mental acrobatics so you would stay excited.

The idea with the swapped rooms is mostly a result of realisation that Kinzo's body has to be hidden in the study -- there's simply no other safe location that allows it to be burned in the middle of an episode otherwise. It is presumably immersed in a preservative liquid in the bathroom, which is numerously hinted at with the 'smell', referred to in every scene where Kinzo is present and even in the scenes where he isn't -- Jessica refers to grandfather stinking up the house like this happens often, where, in fact, it couldn't have happened for a year. Eva actually accuses Natsuhi of killing Kinzo and tossing his body out of the window, which Battler 'destroys' by claiming Kinzo must have hidden under the bed. For a reader who is just starting to read the whole series, Natsuhi is a natural target of accusations, (gun holes in skulls with stakes inserted later, Kinzo's body, last alive all the way up until she gets mysteriously shot) and Battler defending her is a minor annoyance.

But now we know that Kinzo has been dead, which explains Natsuhi's behaviour rather well. Natsuhi knows something about the murders, even if she doesn't do any of them herself even before the bodies are discovered, and, after having Kinzo's dead body dwell on her mind for an entire bloody year - visiting it daily! - she gets the bright idea to get rid of it in a safe-ish way and confuse the murderer(s) in one fell swoop, and tosses it out the window into the courtyard - where it's just one door away from the boiler room where it is eventually burned. She then leaves the room happy and pleased that the burden is off her shoulders finally and completely surprises Eva, who nevertheless accuses her of doing exactly that and is exactly correct... Only Natsuhi didn't kill anyone, Kinzo was dead a long time before that. The characters actually go out of their way to call the receipt an 'important hint' several times using the same vocabulary as if the author is feeding them those words.

Well, it is, they're just misdirecting us on what the hint is actually about.

But Kinzo's matter is relatively simple compared to the locked room with chain, which recurs in Ep5 in a very similar fashion. Let us assume that Natsuhi's perspective in Ep5 is reliable and both murders are actually hinting at the very same trick used to commit a murder in a closed room with a chain, variations of which we see in several episodes. If I were the writer, having created some really new and fresh trick, and noticing nobody caught it the first time around, I would definitely try to explain it a second time in a veiled way.

Then, this is what the Ep5 scene does: Battler eventually deduced that the murderer was hiding in the closet. This time around, we get Natsuhi's reliable perspective hidden inside the closet, which kills this idea dead because she didn't see any murderers in the closet, but almost all the start and end conditions are the same. We even get another hint of Eva banging on the door while the murder happens and rushing off for the cutter. Notice also that the chain, while treated structurally equivalent to a bolt or latch in most mystery literature, apparently is the key to this trick and isn't actually equivalent to those in Umineko. Why do the rooms have a chain anyway? It's out of place in the mansion, which was not initially built as a hotel. Servants are extremely cautious about entering the room without permission.

So let's go back to the switching rooms... Regarding your particular points:

Originally Posted by Renall

• That people really would assume Eva and Hideyoshi went to the same room.
• That the person who is the killer actually knew this.

They definitely would, if Eva and Hideyoshi spent the previous night in their usual room. The killer could know the room changed, for example, if it were originally his or hers own room, and Eva and Hideyoshi were found there unexpectedly.

Mind you, that raises the question of why Kanon and Kumasawa, when visiting the storehouse to get the cutter, do not notice that body or bodies that should be there are missing, but they suspiciously do not mention bodies in this scene at all, nor react to their presence in any kind of expected fashion -- like maybe, flinching, turning away and getting back to the task at hand.

But from a narrative point of view, that would be a really sneaky way to misdirect us too, wouldn't it? You read through this scene, fast, excited - the murderer is trapped! Time is of the essence! How will he get away?

Originally Posted by Renall

That the killer knew the doors would be mixed up by any innocent persons (either of Kanon or Genji must be innocent for this theory, as otherwise it's much easier for them to simply lie to cover for the killer).

Reading the text when I'm a bit more awake, I discovered that the killer could make sure this indeed happened.

Genji never locks the first room he checks, nor closes it, it stays on the chain but that's it. As chronotrig points out, he doesn't pick up the letter either, he uses a handkerchief to pull it out and get a better look at the seal, but the letter remains. The text says 'A light seeped through the crack of the door.' which is only possible if the corridor is substantially darker than a lit room. That would make an open door with a chain on visible very plainly and obviously from either end of the corridor a great distance.

So the killer, to misdirect them about the room, only has to turn off the lights and TV, leave the room they were in, unlock the painted room and push the door to stretch the chain. It is now the only room in the corridor with light pouring out of it, not just the one with a conspicuous white envelope next to it.

As a side note, Beatrice tells us later of all of the doors that exist on Rokkenjima, none has a crack through which a key can slip, and wax seals, particularly ones that can fall off the envelope completely, would make a letter thicker than a key. Which means that it wasn't stuck out from inside the room but was added to the room later, but that's a minor point which probably isn't well related.

Originally Posted by Renall

That the behavior of the people who found the letter at the decoy room is predictable (this requires either prescience, or a "handler" among those expected to discover the decoy room who will send the innocents away so they don't discover the "real" door and who will not take the letter away).

Not necessarily. We keep forgetting that these people are relatives and employers/employees who had numerous opportunities to study each other's character and formulate expectation theories about the most expected behaviours in a tense situation. This, incidentally, is what a chain-locked room creates -- it appears to the visitors that the murderer has to still be inside the locked room.

The whole reason why I think that the switching rooms trick may be, in some fashion I do not yet know myself, (Yes, yes, I'm assuming trick X. ) a key to this particular room mystery (Please, everyone who thought that I provided a complete theory for it, excuse me, I really didn't. I just have an idea which I'm hoping someone more versed in the genre can complete. ) is that it feels like something that can be done on the spur of the moment, and follow naturally from a single choice made in particular by Eva, which, nevertheless, can and usually will recur. "I'm worried the servants know where I sleep so I'll move to a different room today." Pieces do things according to their nature.

In my imagination, one way it can play out is like this: The murderer just chanced on Eva and Hideyoshi in a room #2. Eva and Hideyoshi moved there, while the murderer thought it was free and was their own hiding place. He had to kill them (with a gun -- Hideyoshi first because he found him in the bath, then Eva came in and dropped onto the bed with her shoes still on) there and then because they knew him for someone who should be dead that actually isn't. So once the deed is done, he is busy painting up the door of the room #2, taking his time, and just about when he's almost done, he hears Genji and Kanon coming up from the corridor. Quickly, he darts into room #1, locks and chains it -- and the TV and lights are on because Eva and Hideyoshi did it earlier for safety. He's trapped! Might have to escape through the window, not a pleasant prospect. But Genji and Kanon leave. He goes out and notices that he dropped the letter.

He knows they'll be back soon with the cutter because Genji orders that rather loudly while the door is open and protected by the chain. Not much time to do anything, but he notices how obvious the door is in the twilight of the corridor, and gets the bright idea -- and sets up room #2 be the lit one. Then he hides in room #1.

How exactly does he create a room that is chained from inside while being on the outside is the real important trick here, but I'm pretty sure it's possible because of how often it recurs in the future episodes. It should somehow be possible without actually breaking the red that protects other rooms of this kind, and is the fundamental trick that Beatrice discovered and gave to Lambda in an envelope in Ep6, if my spoiler memory is correct.