The reason I wrote my blues like that was to avoid repetition. I could’ve used those same building blocks to write like 12 different lengthier blues that share the same basic ideas except in different combinations, but that felt inefficient.
While I still don’t believe this is the solution, the red about Mashu being under constant supervision while they were searching the first floor does not cover the period of time right after they left the crime scene but before they split up into groups to search for the culprit. Also, wasn’t the search done on the second floor? I thought there was the ground floor, the second floor, and the attic. In any case, you could always deny this possibility outright by simply stating Mashu did not unlock the door to Ritsuka’s bedroom before Ritsuka’s body left the bedroom after the bedroom door was locked by Ronove. I wonder if you’ve neglected doing so on purpose.
Robin never leaving the room until the moment he died is interesting. Just to engage in some superfluous nitpicking, I might as well ask you to confirm that “the moment Robin died” is not a timespan long enough to go outside and unlock the door.
Ritsuka’s corpse is not in the rose garden? Fair enough. The bedroom includes a bathroom and Robin actually washed the tiny pieces of his corpse down the drain. If at first you don’t succeed, just go sicker.
Right now, I don’t have any blue standing that would explain how Ritsuka left the room, so this is not really that meaningful to bring up at this point in time, but regarding the rooms he could’ve gone to should he have left the room, isn’t there a third bedroom that was unoccupied? The narration never mentioned that the bedroom of Mashu and Nitocris was investigated, so he could’ve gone there and be murdered there, but the current reds seem to block that possibility in other ways.
Nitocris not killing anyone is pretty severe indeed. Severe enough to give me a reason to reconsider some base assumptions. Right now, both the death of Ritsuka and his body leaving the bedroom are sealed behind a fairly solid-looking wall of red. So, let’s circumvent the entire issue. Repeat in red: The deaths of Ritsuka and Robin refer to physical death, not a death of personality or anything else that could be referred to as “death” which still allows their physical body to move around on its own volition.
Also, regarding Robin’s death, which I would assume is an actual death, Robin was killed by Mashu during the night. Nitocris simply opened the door to her and created the closed room after she had left.
Additionally, just in case nothing above sticks… repeat it in red: Robin was not resummoned after his death. It would be devious if Robin had actually died, but then was resummoned for the purposes of escaping the closed room. And then died again somehow. I don’t quite know how summoning Servants in F/GO works, so maybe resummoning like this would not be possible in the first place.