Aw.
I guess she had been putting up with Mukos shenannigans for a while to get this frustrated.

Who isn't. She really needs to learn how to fight.

well the sister is getting angry due to that she she cares about Muko and she doesn't want Muko to get into the fighting ring and get into anything she deems as harmful or bad in her opinion. Hence she get upset and out of that heated frustration she tossing the pot full of flowers and breaking them.

Yeah i got that but at the same time, Muko needs something in her life to be inspired and i guess that normal jobs aren't for her.

Indeed. I have always supported Muko dream to be a combgal and admire her determination, despite that she has a lot going against her. This includes her lack of experience, her being something of a ditz, her perverted ways getting further in the way of any sensible thinking when possible, her disapproving sister, her currently having not enough money (she lost her prize money to pay for the damages to the cafe), and some possible unknown problem(s) with her manager. It'll be exciting and interesting how she would move forward.

That has gotten dramatic all of the sudden!! The big crap!!!!!!

She has a point, you know. I get the impression this happened a lot of times before.

I do hope Muko appreciates her sister...

Uh where did that glass of flowers come from? Also Saniko shouldn't smash a glass like that, you're going to get pieces of glass everywhere and someone will have to clean that up and potentially risk cutting themselves on glass.

You're right that she should have not picjed up that pot of flowers and smashed it into the wall, but this was done to show how the more highlight dramatic and dead serious the sister has gotten in her frustrated attempts to drive home how disapproving she is about Muko's combagal dreams. it's based on the Dramatic Shattering trope.

Oh boy this is not good

Yeah, but she's not gonna get it across by losing control of her own impulses like that. She has to balance her "concern" with consideration and restraint.

Just looking at her actions within the first few pages, I can somewhat tell why Muko is so dismissive of her views; it's because she learned that dismissive nature FROM her sister. Rather than asking Muko to elaborate on what happened and getting a full version of her views first, and then working pros, cons, and potential alternatives, Muko's sister instead chooses to superimpose her own views on Muko's dream in an attempt to deconstruct it, using childish tactics such as slut-shaming and comparing Muko's dream to a similar, but unrelated one in the past. She shows little concern about how her words might actually affect Muko, and throws a shit-fit here when feels like she's not getting what she wants.

I have to agree with your critique of the sister's angry concern, though of course she would have done so without tossing and smashing her own pot of flowers against a wall.

again I have to agree. She can drive even the most sensible people around her nuts with her decisions.

Muko needs to incest her sister and her mom.

That went out of control very quickly .