Jiang Shiyu did not look at him. Her gaze rested on the gravel path ahead, carpeted in gold by ginkgo leaves.
"Because when you smile, your eyes don't."
The wind swept through the ginkgo branches, stripping off the last few leaves. One landed on Jiang Shiyu's braid, unnoticed.
Kannazuki's steps faltered slightly.
Duchenne's smile theory from the psychology of microexpressions instantly flashed through his mind.
Humans could not consciously fake the contraction of the orbicularis oculi muscles.
He had always known this theory and believed his precise muscle control made his disguise perfect.
Yet this girl, who could not even draw a proper force diagram for physics,
had seen straight through his flawless disguise with some kind of instinctive intuition.
Jiang Shiyu's fingers tightened slightly in his palm.
As if she were making sure he was there.
"Your smile always looks beautiful, more beautiful than anyone else's.
But I always felt something was missing. Then one night, I was scrolling on my phone.
I saw something that said truly happy people's eyes curve when they smile.
It made me think of you. When you smile, your mouth smiles, but your eyes stay straight."
She stopped and turned, staring directly at him.
"It's... almost like you're acting."
Kannazuki stood still.
It was not that he did not know how to answer.
Within 0.1 seconds of her saying those words, his mind had automatically generated fourteen possible responses.
They included defusing the situation with a lighthearted joke, changing the subject with academic theory, and even showing a measured amount of vulnerability to win her sympathy.
But he did not say a word.
Because he did not know which response could handle the look she gave him next.
Jiang Shiyu added something, her voice quiet and trembling slightly in the cold winter wind.