I'm not sure about the context of that last shot. At first I thought maybe Akari's Manager (who is the son of the Owner) got a little excited and forced her to continue. But the caption on that last page specifically references "couples", which makes me think maybe this is after she got home. Plus the Manager isn't wearing a cockring, while the guy at the end is (and we've seen Takayuki do that). Either way, she seems to have been really turned on by the situation.
And although I feel like p8 would have been better as the starting page, I think Sensei has it where he does to put a little space between the scene with the Manager and the scene with Takayuki. (Really it would have been clearer if he'd started with p8 and added another page with her coming home and throwing herself at Takayuki.)
CopyOf I see. then it was takayuki at the end, it would make's no since for her to cheat when takayuki has a huge dick, But I would understand if it was takayuki's father.