Now that Yuhi mentioned it, it surprised her when she found out they attended the same school. However, she should have realized that he would enroll in a liberal arts high school.
Out of all the ones in Tokyo, why would he choose 'Iro road'? There were other top-rated art schools, so Sumire knew the chances of meeting him were slim.
It shouldn't have been possible to meet. It may have been the initial surprise that kept her from speaking with him at first. But even then, she could have spoken to him properly. However, ever since he broke into her apartment that night, old feelings she had locked away had resurfaced. Of course, those feelings then were mere recollections of the past. At that time, she was with Mamoru after all.
That feeling was hard to describe. But even now, she remembers it so well. So when she saw Yuhi again it all came back.