Sakura
A momentary look of disappointment came over Sakura's face as the man withdrew his hand, reaching into the cape for the remote. The captive girl screamed as the shock flowed through her sensitive nipples and breasts, the pain an entirely expected result of her defiance but, nevertheless, very unwelcome. Yet, despite the pain and her arousal, and the part of her that said it would be far, far easier to just submit, like she always used to, Sakura remained resolute. She would not allow herself to return to her old, submissive mindset, nor would she allow this man to break her spirit.
Instead, as the man pulled out what looked like a weight from his cloak, Sakura glared at him defiantly, trying not to let the fear she felt show. As she had expected, he attached the rope to the chain connecting her nipples, stretching them slightly and causing a momentary look of pain to come to her face. Yet, to her surprise, the weight appeared to be remarkably light, and was having little real effect on her.
Sakura winced as her captor pulled out the remote once more, expecting another shock. Instead, though, she felt a sudden, extremely painful tug on her nipples, as if the weight he had attached had suddenly grown many times heavier. Not expecting the sudden pull, Sakura found herself bending slightly at the waist as her breasts were dragged downwards, letting out an agonised scream. Despite the agony, she rapidly composed herself, retaining her posture and forcing the weight to stop falling further, her breasts stretched downwards by the force exerted on them. Her face screwed up with obvious pain and her eyes began to water as she began to let out irregular moans. It was obvious that the very heavy weights were agonisingly painful.
Yet, despite the pain, she still remained defiant. As her captor mocked her once more, demanding "proper" defiance, an idea came to her.
Well, let's give him some "proper" defiance", then..., she thought as she moved her hands to take hold of the heavy weight, relieving the pressure on her tormented mounds.
"F..fuck you!" she replied, glaring at him with a smug look on her face as the pain began to disappear, her hands and arms able to handle supporting the heavy weight far better than her sensitive mounds could.
Shirou
Shirou continued to watch the sight with a mixture of arousal and distress. Sakura's screams of pain as the man tortured her made his dick throb once more but, also, brought a tear of despair to his eye. Even so, he couldn't help but feel proud of her, and of the mental and physical strength she was showing. Even so, he was desperately worried, knowing that her torment would only worsten, a feeling made clearer by the addition of the apparently-heavy weight, which seemed to work by some kind of magic.
Once more, though, he was heartened by her defiance. He knew she was strong, and she would surely last for a long time. All he needed to do now was to find a way to escape, to rescue her before her inevitable death at the hands of the cruel pervert who was torturing her.