Kazehara Tetsu picked up the empty playing-card box from beside him.
"After the 208 pieces have been torn apart and jumbled together..."
"We'll randomly draw 50 pieces."
"These 50 pieces will be stacked inside this opaque box in the order they're drawn."
"Then we'll put the lid on."
"These 50 cards will be 'invisible.'"
Even Katsuragi Kouhei, who was watching from the sidelines, had trouble following.
"So..."
Katsuragi couldn't help interrupting. "We have to find the pieces outside and guess what's in the box?"
"Exactly."
Kazehara Tetsu nodded, but his eyes remained fixed on Miyabi Nagumo.
"While we search for pieces outside the box, we also have to keep a mental model of what's inside that 'black box.'"
"For example, if someone names the number '3'..."
"The challenger has to find the pieces belonging to '3' among the scattered pieces outside, and also search their memory... to see whether any of the 50 pieces placed in the box belong to '3.'"
"If there are any, which position are they in?"
Miyabi Nagumo frowned deeply.
The players had to carry out an intense external search while maintaining a hidden list of 50 items in their working memory.
But that wasn't all.
"Just remembering the positions would still be too easy."
"To prevent people from simply memorizing them..."
"We're introducing the 'Dynamic Displacement' rule."
"The cards inside the box absolutely cannot be revealed for confirmation until the answer has been finalized."
"Let's say..."
Kazehara Tetsu reached out and sketched an imaginary box in the air.
"Let's say I'm absolutely certain that a certain piece of '3' is in the fifth position inside the box."
"But I can't simply say, 'It's in the fifth position.'"
"The rule requires us to perform a virtual displacement based on the additional instruction given by the person