I like this as it does make use of descriptions and translations and so on that I've come across or read or had explained to me over the years! Its origin is not to be found in the home of Karate (Okinawa blah, blah..) true, that single point comes up each and every time, what also comes up every time is the military and/or docks connection and origin. The Kyokushin connection is mainly due to Sosai use of it in his training and teaching of Karate. The connection here is WWII, Sosai famously said in a television interview, "Itsumitemo Haran Banjyo" (Nihon Television), Osu is common in MA, in as well as outside Japan, but even so it is still considered by some to be 'guttural' (harsh) less than perfect respect, and in Okinowa its association with the underworld persists even to this day!