He doesn't let himself visibly wince, but he's doing it on the inside.

"Nah, I'm used to stains. And what convincing? It WAS worth the trouble!"

With a final, exaggerated inhale and exhale, he stops leaning on Kanji and takes a step back. He's still breathing a bit heavily, but he's composed himself otherwise.

"Thanks for letting me use you as a wall, stranger!"