I have a similar story involving my kid. When she started 6th grade (first year of middle school here) it was a radical difference, riding the bus, dealing with 8th graders, etc.
The school had said they had a zero tolerance policy towards bullying, and when she came home after the first week and told me the sexually charged harassment she got on the bus, explaining it to me in tears, I called the principal.
That guy couldn't have taken it more seriously. The offending (and offensive) kid was yanked out for a week, and his parents were notified that if it ever happened again, he'd be expelled.
That was both a shitty and great week to begin my relationship with the school.