[Enough of this petty teenage rebellion you little brat!!! Which is to say, any time Kaoru seems like he's starting to get a handle on things, the overseer nods to the arm-twister as a signal to pop that shoulder right out of its socket again, because the Nagumo clan is full of douchebags, basically. This is partially punishment for having the nerve to go behind their backs, and partially to keep him so focused on the pain that he won't have time to realize what exactly they plan to do with the poison, and thus, won't have the opportunity to try and help.

Once he is sure Kaoru is settled in and restrained, he'll mosey on off to report to the clan head because that man sure does need to know what his wayward "daughter" is carrying on with.

Sen tries to tug herself free from her captors as they drag her out, but whether it's that she's weakened from her stay here, they're just stronger than her, or some combination of the two, she isn't able to do so; they only have a minimal struggle with getting her exactly where they want her. She doesn't need to hear him speak to have some idea of what he plans to do. The fact that he'd brought the bag along at all rather than just dropping hints that they'd found something of hers in Kaoru's possession had already been enough for her imagination to leap to the worst-case scenario that they might force her to take it.

She snarls as he opens up the bag.]

I do hope you have a convincing explanation for why the only thing you'll have to give any future visitors from Yase is my corpse.

[...but after that, she keeps her lips firmly pressed together. She doesn't plan to make it easy for them to get her to take it.]