"As their brother, I've got to do my best to protect their smiles."
Not really. They have their own responsibilities.
A 20 kg backpack isn't that bad. It's about appropriate for a woman's hiking backpack.
"Look at her! She's got cat ears!"
So the lizard man (woman?) didn't catch her attention?
Introducing themselves as sisters he loves very much is rather narcissistic.
They're extremely judgemental.
"But we can't lose to her now, can we?"
You've been losing since you appeared, and you have no chance of winning over her.
"A ridiculously huge chicken that can't fly," is a very accurate description of that birb.
Yeah, fuck those sisters.
They don't really know that he made connections and she gut punched him just because he started talking to a girl who isn't a relative and is same age as him.
And that's absolutely fucking retarded. They don't own him; they owe him.
He's trying to sell off her chocobo, what would you do in her place?
Say something. At all. She was quiet the entire time, and then suddenly slugged him. But if violence is her first reaction to anything that displeases her, anyone having a problem with her should introduce a fist to her face, then tell her what's wrong.
She wants an isekai giant fluffy chicken pet.
Then
she can take responsibility for it,
without relying on her brother.