I guess it's implied that Midori go through with the break up and allowed Shiho, Chisa, Haruka, & Sayaka to be Reiji's sex friends. I think it's also implied that Chisa didn't visit her boyfriend during summer since she's joining Reiji and the girls in orgies that she probably broke up with him offscreen. The hentai was wholesome and funny but the best part of the hentai was its music, it really fits the mood in different scenes. I'm surprised that Sayaka is the only bi one of the siblings instead of both her and Haruka. What doesn't add up is why was Chisa in school atnight during Midori and Reiji's 1st time?