I’m no expert on this, but in addition to the other factors people mentioned, I would say that people in Japan seem to pay a lot more attention to high school sports. The Koshien Stadium and the high school baseball tournaments name after it are very famous. I’m not even interested in sports, but I know about them and often notice friends talking about them online. I know absolutely nothing about the college baseball tournaments or where they’re held.
When I had sex ed in the late 90’s, I was shown videos with real (but obviously non-sexualized) nudity. I don’t remember there being any controversy about that at all, and I went to a Christian school (Anglican).