I wonder if the little sister will ever learn empathy and understanding that others don't necessarily like not being relied on at all. Humans are co-dependent.
Edit: As an aside, the brother is quite tall for being Japanese. He's 178cm compared to the average height of 171, plus he's just 17 so will likely still grow a couple cm more. So if he just cuts his hair short, and also go for a bearded if he can grow a good one, he'll be quite handsome. He has an old face, but that's something you can use to your advantage.
Edit2: I don't think I've been this uncomfortable reading something in quite a while.