You know what really gets me? People who think Yuka is just a whiny bitch. Some people even say she’s dumb for whining about her brother until the bitter end, but that is in fact EXACTLY what makes her so special. Bitch about it all you want, the fact of the matter is, it saved her from Yuuya in Mire.
I think if she had agreed that he was her big brother (at least, once he had her tied to the table), that actually would have sped up the process, and he would have ended up murdering her. What’s important here is not simply that she didn’t cooperate with his wishes though, because Mitsuki did the same thing, and that did her no good at all when she became Yuuya’s victim. So why did it work for Yuka?
The difference is in HOW they resisted. Mitsuki, after originally screaming her head off like any person would do if they were being stabbed to death, forced herself to keep quiet after a while. This frustrated Yuuya not only did he not got his way, he didn’t get his way because she was deliberately suppressing her true reactions specifically to spite him. It was a lie in the purest sense of the word.
Then we look at Yuka’s actions. Far from suppressing, Yuka was very vocal about all the things she felt, good and bad. And one thing she kept repeating over and over (aside from calling for her real brother) was that Yuuya was NOT her brother. And Yuuya, deep down, knew this was the truth. With the help of the darkening though, he was able to convince himself otherwise for quite some time, but again and again Yuka chipped away at his delusion with the one thing he had always craved most from life: the truth.
And in the end, she wore him down. While Yuuya initially dismissed her cries for her brother as silly because he was right there with her, In the end, she called for her brother so much that Yuuya finally snapped and asserted than her brother wasn’t coming.
It was that EXACT moment that his head started to really hurt. That’s when everything started falling apart for Yuuya; because he had finally admitted aloud that he wasn’t her brother. Everything came crashing in from that point forward, up to his last breath. And the pain just mounted more when Yuka continued to be the picture of innocence and truth, asking him if his head hurt and offering him medicine for it.
Yuka is so much more than your moe little fetish fuel. She is the embodiment of something the school sucks most people dry of.