Just a nitpick, but on page 2, rather than quotation marks within quotation marks you should use apostrophes (') for anything between the main quotation marks.
For some random examples:
"He claimed he had 'resolved' the dispute through 'forceful negotiation.'"
"I heard her mutter 'It wasn't my fault' before she left."
So Karin's basis for what's "normal" is what the heroine of an in-universe work of fiction could do? Oh dear.
I will also note that Japan slander laws being as nasty as they, the friend just talking about what Black Shell did to the intern is probably grounds for them getting sued.
In the US, it's not slander if it's true.
But in Japan, it's still slander even if it's true.
Muscle Brain decides the answer is more Muscles. Muscles will never betray you.
As a minor, I'm not sure she can even legally enter into a contract that exploitative. Maybe if she got the mom to co-sign, but even then, there are limits to what can be signed over. I really have to wonder what she was told, versus what was in the contract.
The solution to everything is raw, elegant power. And now we know why her sense of normal is so utterly warpped, she's literally taking an anime as a base level.
Karin firmly believes with her pure ojou-sama heart that explorers on the level of Dungeon Alive are somewhere out there in the world, fighting the secret fight for the world.
This doesn't seem to be in the original WN/LN though; so unsure where it came from.
But yes, she judges her item box by its limitations compared to the one she saw in Dungeon Alive! and by those standards, it is lacking - it is relatively small, can't be used to swallow an entire attack or explosion, and isn't transferable to other people.
She believes in the "upper tier explorer world" of stupidly OP characters, as shown in the show. And can't be convinced otherwise.
Biggest problem with convincing her though is that she isn't, in fact, wrong. As is hinted at by the conversation Mayufu has in Ch.22 with one of her former co-workers