Probably because Tanned Athletic Sharktooth Tomboy Wingwoman isn't an anime/manga fan (choosing the active sporty life and all) and therefore doesn't know what "anime" is.
Yes, even young Japanese people living in Modern Japan can be unaware of the massive pop culture phenomenon that is anime. Shocking, I know.
Since there are only 3 chapters left to read. Imma drop this and put it in my plan to read list. I know myself and I feel like this rivalry isn't going to end soon and is just going to end up annoying me