In chapter 25 of The Boys, Kyuhyun said how stunning and eye-catching  Yoona was for him after he saw her.

Kyuhyun's POV

One big question is still on my mind. Who’s exactly this girl is. Why is she always being there wherever I go?

When I go to cafeteria with Changmin and Jonghyun, she’s there giggling in the corner with her two friends. When I’m watching my basketball team who are practicing, I see her looks so happy on the edge of the court. When my homeroom teacher calls me in the teacher room, she’s also there talking Kim Minji seonsaengnim, who I assumed as her homeroom teacher. She’s also waiting for bus in the same bus stop. And as I expect, we ride on the same bus.

I don’t know why I see her everywhere. It’s so weird. Maybe because she’s pretty so she looks stunning amongst other. But I don’t really agree with that, since so many pretty girls in my school. Or maybe, without I realize I always look for her?  Well she’s pretty also cute, and that’s all I really know