One example that immediately comes to mind is the style Goju-ryu and how politically active many of its members were before and during WW II and also were high ranking officers in the Imperial Japanese Army. This of course brought about a lot of distancing by the Japanese community from that group at the end of WW II and I have attached a web site you might find interesting outlining this. This was one of the the reasons why martial arts schools in Japan were shuttered at the end of WW II during the American military occupation for several years and the instructors registered. It is further thought that this is where the idea of your hands and feet being registered first originated from which of course carries on today as an urban myth to some extent. There have even been some books written about this that you can also research.

http://www.imgka.com/index.php?option=co...

I don't know this as a fact, but I heard that Karate was a style created by the working class culture

Marginal at best. It originated in Okinawa, which has a separate language and culture from mainland Japan, and so is kind of "foreign". The native Japanese martial arts are grappling-oriented (Sumo, Judo, etc) and karate has a very different "flavor"; neither was it passed down from the ruling class of Japan.

I lived in Japan for 3.5 years, and karate was mostly treated as a sport over there. There was an emphasis on strength. The guys who won matches, they didn't really talk about their technique as much as, "Oh, he's very strong".

It can be one of the doors that opens to bushido...wakarimasu, tomodachi?