There certainly is an obsession with rockabilly dancing in Japan.
A well-known dance group, who dress as though they just walked out of the 50s, operate in Harajuku. They largely consist of rather old dudes, who probably were around in the 50s. You can find them twisting and shaking at the entrance to Yoyogi park on a Sunday. If you Google "Harajuku rockabilly dancing" you will find an abundance of videos of them, taken by surprised tourists.
However, as much of a novelty as these guys might seem to be, the obsession with rockabilly dancing is not exclusive to Harajuku. It is actually very common place in many parts of Japan. In fact, I'm starting to get the impression that most universities, institutions and towns in Japan have a rockabilly dance club. Almost every festival I have been to has had a group of rockabilly dancers. Just men, just women, men and women mixed, matching outfits, leathers waistcoats, petticoats, polka dots, sideburns....spend one summer in Japan visiting numerous festivals and you're likely to get your fair-share of rockabilly dance performances. I remember being very surprised and slightly confused to have found 4 separate rockabilly dancing groups at the Mito Matsuri last year.
I don't know what has influenced this movement, or why it is so popular, but I do know that it is awesome!
Here is a short glimpse of some rockabilly dancers I saw at a beach party at 海の家 山形屋 (Yamagataya, Ajigaura beach, Hitachinaka) last night: