Books like Sundome, Vol. 4

I have really liked this series so far, but by this volume you can really see that they are trying to stretch this story as far as it will go. We don't really get any new information about Kurumi's mysterious illness or who her older friend really is. Instead, it is more of the same (Kurumi humiliates Hideo, then she does something nice for him). I am ok with repeating plot points, but if the overall plot doesn't advance, then what's the point? I believe that this series ran for eight volumes but, by volume 4, you can really see that they had enough story for maybe half of that.