The group chat will be on the app Kakaotalk (it’s free). Why? Because it’s free, tumblr doesn’t allow gc, and it does not require me to know your personal info other than your username.
1. Create the an account with kakao. Preferably use the username that’s associated with the tumblr account you reblog ICoS stuffs.
2. Send me your username so I can add you to the group chat. And you are done.
kakao is available on computers also