Erg. I know that there has to be some sort of conflict, otherwise there's nothing to build a story around, but Kase-san's complete obliviousness to Yamada's concern about senpai makes one feel that Kase is an idiot and therefore less sympathetic.
Yes, I know, I know. If Kase and senpai never had that type of relationship, it would be harder for her to imagine that Yamada thinks that they did. Still, she should be able to recognize by now when something has Yamada feeling miserable and insecure, because that seems to happen every week.