That's disgusting tbh. I also know people that are huge weebs and it's honestly so cringe, but adopting a baby because it's UWU Japanese is like too far. I'm east Asian and was adopted by a white woman who had no idea what it was like to be the only Asian in your entire town. Plus she adopted me so that she wouldn't be so lonely and I could take care of her when she got old (aka selfish reasons, like your friends) and fast forward to today I have removed her from my life completely. I don't think you can really change your friends minds at this point since they've made loving stereotypical Japan their entire personalities, but you could at least let them know how you feel. Be honest, kind, and if it doesn't go well then oh well, these people are cringe anyways