I don't understand (Soukou Akki Muramasa)

Currently on Ichijo route right now, and as you may have guess, I did not intend for this to happen. I'm but a simple man, when I see a big breast mommy type character available as a heroine, I cannot help but go right after her. >!Then, I did what I did and holy shit... still can't believe it. The cursed rule of balance, just as it has been warned at the very beginning. But, honestly? I didn't loathe it. Just kinda thinking it's that kind of factor that would help me sympathize with the protagonist more. Plus, it's pretty unique and I adore that. !<

REGARDLESS, please respect my choices if you're going to implement that mechanic. >!Around the final act of the dual between Masamune and Muramasa, when Kageaki was about to unleash Railgun, he got several flashbacks about Ichijo, one of which was a CG that I did not have any knowledge about. It's weird of course, because all my choices was Kanae and Kanae throughout. !<Why? Really, why? I know it's not that disturbing or anything but it left a bitter taste on my mouth. And the more I think about it, the more I'm weird out by it. Is it me that is flawed or it is the game? What happened?

P/s: I'll try to ignore it for now and continue with the game but if I'd be very appreciated if someone could give me an answer without spoiling anything. Also, sorry for the inconveniences if this has been asked before, I'm too afraid of spoilers to open any thread related to the game right now.

Edit: This is my first playthrough.