Meh, this doesn't do it for me. The setup is way too artificial, it's totally unrealistic for somebody's first statement towards the person they're going to be living with to be calling them a dumbass unprovoked. You could say it's a stage persona without trying to deny your new sister a chance to even get along with you.

The main thing I think you are forgetting is how different she is to her stage persona - how she thinks those kinda fans are dumasses for believing she is that kinda person and probably resents them and the role she is stuck in- and she KNOWS her new sister is one of the most fanatical and therefor gullible of her fans.

Ofcourse she is gonna hold her in very low esteem and does NOT want her bringing those stage expectations into her home- probably the one place she can be fully her real self.

That is obviously also just her real personality- she is a realist / pessimist- and seemingly just not open to being friendly with her atm. I dont see anything unrealistic about it really,

even so, instead of getting friendly with her new sister, confiding in chika about her job so that they both get to know each other better, akane chose to be rude, calling her new sister Dumbass, Pig?
Is that what you call reality?
Nonsense, bullshit!
How long has it been? What? I ask you? How long has it been since you talked to other people and let your normal thinking become silly like this?
build situations that are too contrived, artificial, and unfounded. it's so bad but you still consider it realistic?
touch the grass!