"This message feels strange somehow."
Yuki stared at a note from Riku.
"How so?" Aoi peeked over.
"The content is normal. But oddly roundabout."
Aoi became interested. "Maybe steganography?"
"Steganography?"
"A technique for hiding information. Unlike encryption, it hides the message's very existence."
Riku approached. "Caught?"
"I knew you were hiding something!" Yuki exclaimed.
"Actually, if you read the first character of each sentence vertically..."
Yuki tried. "'Sorry'?"
"About yesterday, I wanted to apologize. But saying it directly was embarrassing."
Aoi smiled. "Classic method, but effective. Surface message and hidden message—a two-layer structure."
"Information-theoretically?" Yuki asked.
"The channel capacity is divided for two purposes. Explicit message and implicit message."
Mira showed a paper. "Explicit and implicit."
"Yes. Human communication always has these two layers."
Yuki thought. "Sometimes the implicit information is more important?"
"Yes. Word choice, silence timing, sentence length. All carry information."
Riku wrote in his notebook. "So the real message is outside the words?"
"Not outside, but in the margins," Aoi corrected. "Between words, in context, in implicit understanding. These constitute the whole message."
Yuki asked, "How do we read that marginal information?"
"Mutual information is key. More shared knowledge means more can be conveyed with less explicitness."
Mira gave another example. Her notebook showed only dots arranged in a line.
"What's this?" Riku looked confused.
Aoi looked and understood. "Morse code?"
Mira nodded.
"Conveying complex messages with just dots and dashes. Ultimate efficiency."
Yuki decoded it. "'Meet at noon'?"
"Correct. Clear message with minimal symbols."
Aoi explained. "This is an encoding problem. Methods for efficiently representing information."
"But," Yuki noticed, "if you don't know Morse code, it's just dots."
"Exactly. Codes require common understanding between sender and receiver."
Riku laughed. "So my vertical reading worked because we had common understanding?"
"Yes. People outside cultures familiar with that technique wouldn't notice."
Mira showed a new note. "Context is key."
"Exactly," Aoi nodded. "The same message changes meaning with context."
Yuki gave an example. "The words 'I'm fine.' By how it's said, you can tell if really fine or actually troubled."
"Prosodic information," Aoi explained. "Pitch, speed, intensity. These also carry information."
"In text?"
"Punctuation, line breaks, emoji. Visual elements supplement prosody."
Riku asked, "So to convey meaning perfectly, you need to consider all layers?"
"Ideally. But perfection is impossible."
"Why?"
Aoi drew a diagram. "Sender's intent, encoding, channel, decoding, receiver's interpretation. Information transforms at each stage."
"Information loss?"
"Not loss, but transformation. The receiver interprets the message in their own context."
Yuki understood. "So that's why misunderstandings arise?"
"Yes. But misunderstanding is inevitable. What matters is confirming with each other."
Mira said slowly, "Meaning is negotiated, not transmitted."
Aoi nodded deeply. "Meaning isn't transmitted. It's constructed through dialogue."
Riku laughed. "Difficult. But that's why conversation is interesting?"
"Yes. Perfect transmission is impossible, but that's why dialogue continues."
Yuki closed her notebook. "I'll pay more attention to message margins from now on."
"Good attitude. But," Aoi added, "be careful not to over-read. Sometimes margins are just margins."
The four discussed what lies behind words in the sunset club room.
Truth might hide in the margins more than in the words themselves.
But reading those margins requires understanding the other person.