You live in a private school with your friends and other classmates, one day the principal comes to you and you all stand up

Principal: I want to introduce you to my daughter. She'll be your new classmate from now on! Come in!

The door opens and you see tall girl with dark hair and eyes, she is very similar to the principal and has a severe look, it seems like she has never smiled in her life

Kokoro: My name is Kokoro, dear students, I am proud to be among you as a classmate and friend