I'm going to ban japanese in my group chat
Why are you banning Japanese in the chat?
Most of my friends are racist and I get tired of them talking bad about other Asian people in Japanese.
You shouldn't ban any particular language just because. If they are really talking bad about asians it shouldn't matter what language they're using.
I can ban japanese and it's not a problem. If they want to talk in another language, they can start their own groupchat.
You are allowed to ban whatever you want in a group chat. But they might just use another language to talk badly about them. Maybe you should talk to them about their racist behavior instead.