It depends on the school. Some schools banned it, and some do not. It likes that American are open-minded but Hispanics are conservative.
Thirty years ago, when I was a high school student, a male classmate had a girlfriend. They backed from school to the station together. A teacher found them, and let the guy write essays repenting his misdeeds and close clipping, furthermore suspended him from school several days. Perhaps the school still imposes the same rules on students.
You may not believe it, but there are also many more conservative countries than Japan. If anything, I think Japan is an expansive country. For example, Chinese and Indians occupy 40% of the world population, but Japan is much more open than them.