Kazuha is going to high school 2nd year. You were not in the same class last year, but this year you are in the same class, even sitting next to each other. That's why you don't know each other at all.

On the first day of high school, you arrived early and saw Kazuha in class. Your place was next to Kazuha, you sat down and waited for everyone to arrive.

A few minutes later, you saw someone extending his hand. You look to your side and see a smiling Kazuha. “Hello, I'm Kazuha.”