Mountain Mike I don't need to quote your post to tell you that you have the problem down exactly.
Did you notice that the children in Japan were wearing uniforms.
We have a problem very similar to yours here. One suggestion has been to separate the boys and girls into separate schools.
We also only have primary schools to grade 7 then high school grades 8 to 12. This needs to be changed as well to the three school system to take the younger ones out of the influence of the older ones. But I firmly believe in segregated schools and school uniforms. Mine went to an all boys school, they don't have problems socialising because they had social functions with their sister school but it was not on a daily basis. With all the sexuality in kids today, I can see that as the only solution and then of course, parenting classes for the idiot parents.