Am I the only one that find interesting that Kase, who's head over heals for Yamada, didn't introduce her as her girlfriend to Inoue who's supposedly her ex-girlfriend and thus should know Kase is into girls ?
Usually, you go for the "friend" introduction when you don't want people to figure out your gay. Makes me think that not only Kase never dated Inoue, but also never tell her that she like girls. Well, could also be that she was overly cautious of being on school grounds, so there might be a risk of someone coming within earshot. Also, it feels that Yamada is especially hurt by that introduction exactly because she's so set on Inoue being Kase's ex-girlfriend that she would have feel natural to be introduced as her girlfriend.
As for Inoue, I reserve my judgement for now... She did come across rude about the "don't get in my way" comment, but might just be because she was looking forward to have a proper run with Kase without any distraction and she doesn't like having Yamada tagging along for no evident reason. Maybe she also feels that if she wins against Kase with Yamada around, there's a chance her win might be caused by Kase being distracted by Yamada.
Or, plot twist : Inoue actually has the hots for Yamada as well (the "I" quickly changed to Kase when mentioning noticing her on the side) and would get distracted by Yamada just as much so she doesn't want that. Would be kinda fun, the two of them running around poorly because both trying to sneak peeks at Yamada in the middle of it. XD