I wasn't a counselor, but a teacher for 35 years, in the US. Public schools. I reported to the principal and he carried the ball from there.
But I knew (more timid) teachers who would report to another teacher or to a guidance counselor first. Made me mad when they did this. I had to report for another teacher more than once because...'Oh my goodness,' timid one would say, 'what if I am wrong?'
And so what if you were, still had to report it. I even had to report abuse told to me by my daughter who attended a diff. school in a diff. town. (She'd overheard someone talking about getting a good beating by their dad that morning.) I mentioned it to my principal, for advice, and his response was: gotta report it. Now that I know and you know, gotta report it.
And he did. He reported to the local police, who would investigate and SS, who would also investigate.