This guy really knows how to make someone's blood boil. I hope arata beat ts out of him in a spectacular way
Arata won't, unless his whole character changes.
He saw the bruises on her and tried to question her a few chapters ago and she just said "nah don't worry about it" and he spent several panels thinking "what if I'm wrong? what if those physical marks of violence on my sister aren't what I think they are?" and then just let it all slide doing nothing at all.
Arata needs to get his head out of his ass and actually be willing to throw hands, which he hasn't done up to now that I can remember. Because he's not winning a fight of words/reasoning with this guy, based on this chapter at least.
Until he actually steps up, Banri's on her own.
(Unless the other sisters intervene somehow, which they still think this is all fairytale nonsense so I don't expect that happening.)