I honestly feel bad for Kotooka a little bit. It's like there's no chance to be with her so she just shrug it off and let it go for shiratori.

Shiratori fell for Washio. Washio fell for Kotooka. Kotooka fell for Shiratori... Perfect triangle..

I think it was Shiratori that Washio fell for in grade school. It was said that she looked like a boy in grade school..