The reason is because, at the time it was supposed to air, there was this incident in Japan:
A 12-year old middle school student kidnapped an eight-year old kid, sexually molested him (forensics show his genitals with razor cuts), and pushed him off of a ten-story building, killing him.
As for the above mentioned incident, the revised Japanese law for punishable age was lowered several years ago from 18 to 13 (due to an infamous incident about a 13 year-old kid decapitating a mentally-challenged elementary school kid in Kobe, and putting his head on top of the school entrance). However, the kid in this case happened to be 12. Tough luck. His punishment? Nothing - only a 10 day suspension from school. The mayor of the city put the entire blame on the kid's parents, and they were dragged out into the street to make a formal apology, while the kid probably stayed at home to play FFXI.