According to Sawamura, the sound the ball makes when his pitch hits the mitt varies from catcher to catcher.
"Chris-senpai's is excellent. Wolf-boy's is good too!"
"And Miyuki-senpai's?" Yui asks.
"...perfect," Sawamura mutters, his ears red.
"!"
Miyuki heard that, his face turning red.
Cue Sawamura groaning in embarrassment into a pillow... while Miyuki groans into his hands.