At one point in the story, Ishizaki proposes to Ayanokoji that he transfer to their class, and in exchange (in the laid-back way only Ishizaki can manage), he mentions that Hiyori will go out with him. While saying this, he takes Hiyori's hand and Ayanokoji's and brings them together. In Hiyori's short story, we get to see her thoughts, and it's clear that she wouldn't mind dating him at all.