@jesuscristo zero tolerance policies in schools are actually a fairly recent and fairly american stance on school violence. Like they were coined specifically in retaliation to school shootings etc and have been robustly criticized for their contribution to the school to prison pipeline and biased applications. I doubt that fighting on school grounds wouldn't warrant a disciplinary response, but I doubt they'd go straight to expulsion/imprisonment, like, he'd probably be suspended or something if it was a one-time thing.
@LilYoshiXD From what I've read and heard, irl japanese teachers simply don't care if the student is being bullied. As long as they keep going to school it's all good.
@jesuscristo Just fighting once won't get him expelled also there is no proof that they were fighting, they can just said they fell or something. Unlike in the US, high school students in Japan have to pay tuition fee so expelled them would lead to a loss of income. Unless they committed some serious crimes like being a prostitute or joining a gang, just a fight doesn't lead to expulsion.