beta
Okay so, I'm not THAT upset with the sister. Honestly, as someone with many siblings, if I saw they were hanging around with a weirdo I'd at least try to tell them. But I wouldn't do much more than that, I wouldn't try to convince them after they say they don't believe me. It's clearly just a waste of time.
That being said, she needs to stop trying to get involved. I mean, the dude you just thought was a weirdo saved you AND your friends from being violated. I'd be too grateful to even try or care to get involved again. Especially with how nice he is to haruki, even if it's a facade or whatever she thinks is happening.