According to this article, Yamatsuri's program was based on one introduced 10 years ago by another town, Nishikata, in Tochigi Prefecture.
As I've pointed out in a previous post, declining birth rates are a serious issue in Japan. Just last year, the country's population actually began shrinking.
(Incidentally, the name "Yamatsuri" literally means "arrow festival." A Web search failed to turn up anything about the name's origins. Perhaps it goes back to some ancient festival that was held there, but many place names in Japan are so old that their origin is lost in antiquity.)