My older sister is Racist towards asians and I don't know what to do?

I'm a 16 year old Anime/Video game fan who loves the Japanese Culture (lifestyle, how the country is run, history, etc. and not just for the entertainment such as anime and J-rock). The problem is that I have an 18 year old sister who mocks asian people most of the time and it pisses me off (Both of us are a mix of German, English, and Cajun French). She knows that I'm into that culture and she would pick on me by rudely imitating them in a bad manner. She hates the Chinese and the Japanese but not the Koreans since we have a Korean step-grandmother. I would think thats Hypocritical because if she imitates asian people, that would offend my grandmother. Honestly, I think my older sister is a spoiled racist brat and I don't know what to do with her. Any suggestions?