"Who told you?" Yumika asked, her tone demanding and nervous. "Who told you about my condition?"
"Nobody! Really!" Hiruki said frantically. "I figured it out on my own. After the fountain this morning leaving your bra behind, and then the rain, I took a guess. You never come to class when it's raining heavily. Plus, I pulled your sweater up while taking off your poncho and saw how your top fit. Accidentally, I swear."
Yunika stared at Hiruki, dumbfounded. When she thought about it, the girl's reasoning made sense. If you knew what to look out for, Yumika hadn't done particularly well in hiding it. That left one question though.
"Okay, that makes sense... but how did you know? How do you even know my condition well enough to spot it?"
Hiruki's face flushed a deep red at Yunika's question, and she looked away.