Part 218: (Hint 10)

"What do you mean 'you know what she meant'? Explain yourself...!"
"The culprit of the first twilight really did kill six people. If she had said that at the time of the first twilight, I might've accepted it as it seemed. However, if we remember that she said it after the second twilight, a new possibility shows itself...!"
"You don't mean... that the 'six people who were killed' includes the murders of the second twilight...?!"
"That's it! The culprit really was hiding among the six in the dining hall! Later on, they snuck out of the dining hall, killed the two people in Aunt Natsuhi's room, locked the door from the inside, and hid somewhere in the room...!"

The culprit could only have killed five people at most in the dining hall. However, if we add on the victims of the second twilight, they would definitely have killed at least six times...!

"I see, now it all adds up...! You can construct the closed rooms of both the first and second twilights without using master keys...!!"
"Well, you'd think so, but that reminds me of something else. Aunt Natsuhi's room was sealed immediately afterwards..."
"Yes, come to think of it... Lady Bernkastel used the red truth to say this: the group sealed the room at the same time they left. No culprit joined the group as they left."
"And she also said this: all of the seals will not be broken."
"In other words, the culprit is trapped in a closed room again."
"That theory might explain the first and second twilights. However, the culprit would be sealed inside Aunt Natsuhi's room, unable to leave."
"And that means they wouldn't be able to carry out the fourth twilight and onwards! Gyah, I thought it was such a nice theory, but I guess it's wrong..."
"I don't think we're wrong about this theory, but... Maybe it just needs some more tweaking..."