The thing with Kanao's anger, for me, isn't that she's just lashing out randomly. It's a huge sign of her breaking through years of conditioning. She was raised to be this perfectly obedient doll who only acted on orders, not her own heart. So when she gets angry—like when Doma mocks Shinobu's memory—it's because something has gotten so deeply past that wall of enforced indifference that her own human emotions finally explode out. That's not just anger; it's a victory. It's her claiming her personhood in the most visceral way possible, and it's incredibly powerful to witness in a character who started so silent.
Some folks say it's just a typical 'avenge my sister' trope, but I think that undersells it. The 'coin flip' mechanism she used to make decisions was a prison. Her anger in those key moments is the coin shattering. It's her choosing, without any external prompt, what she values enough to fight for. It makes her later choices, like using the Final Form without hesitation, feel earned. The rage isn't the end point; it's the catalyst that fully unlocks the person she was always meant to be.