Gosh, what a brat. Like the thing with knowledge and knowing things is different from actually applying them daily. And just because someone is being earnest, doesn’t give Mamari the right to be rude. Like it probably is better if she is states from the start that she knows the things that Mc says in the beginning, in a polite way.
I bet Mamari is gonna get herself into trouble where the MC has to save her and only in a life or death situation where she realize that yeah, she’s wrong, would she realize that her attitude sucks.