It's more mature and socially acceptabe than in America. Kids learn sex education and safe-sex methods early on. I mean, look a this
But with all of that aside, condoms are usual practice within married couples. Birth control isn't so. It was legalized in 1999 and still get a lot of negative press from doctors. One theory is that the doctors want to keep the abortion business strong so they discourage the pill. Japan has a 35% rate of abortion.