I bet the main reason Kase-san is excited about seeing her senpai is to brag about Yamada.
Yeah I'm not convinced that Kase and Inoue actually went out. I have a feeling Inoue has a thing for Kase, confessed, and then Kase was like "Sorry, you're an awesome friend, but I'm in love with the cutest potato on earth." Or something like that.