I believe that Kurumi might be the one who "conquers" Shidou rather than the other way around. She's subtly aggressive and he's proven to be extremely weak to her type of personality. My belief is reinforced after reading the latest couple of chapters.
Also, Mana's a potential brocon here. Addressing Shidou very respectfully as "Nii-sama" and all, and what's with that "heart-throbbing when she first saw him" thing going on? It's pretty funny to describe it that way.
