Greetings to all, I am the instructor Robert was referring to. I do get around because I know Darin Hyde, if only from the internet and Roy Hebden and I were in France together last summer.
With regard to the nature of Yoseikan, let me say a couple of things. First, my Shodan and Nidan certificates say aiki on one and jiujutsu on the other. At the time they were awarded, the U.S. Yoseikan curriculum covered both of those areas. That notion of awarding rank was changed a few years ago in YWF, now all Dan ranks read Yoseikan Budo. Shihan Mochizuki has wanted Yoseikan to be its own art for many years and this was a way of putting it all together. There is no more Yoseikan karate, aiki, jiujutsu,iai, etc. even though the test sheets still read in that way. Now, in YWF all are skills under Yoseikan Budo.
I was in a conversation with Shihan a couple of years ago and that is when he stated that he felt his father's work should never have been called aikido but "a soft jiujitsu". I believe that Shihan is correct only because the Yoseikan I was taught here in the U.S. was directly from the Hombu dojo and Dr. Glenn Pack's regular visits there. I guess you could argue the other way, that we are/were a very hard style of aiki. Go and visit an aikido dojo like Aikikai or Schools of Ueshiba and you will see a very different approach to the whole process.
I would like to toss one last thing in here. The Seifukai do not teach Yoseikan. They may teach principles that were taught by Minoru Mochizuki but they do not teach Yoseikan. The words Yoseikan were taken off of the building several years ago and O Sensei Mochizuki, before he died basically denounced the entire idea of the seifukai. Sorry if that hurts feelings, it is not intended to, only to clarify the position of Yoseikan World Federation with regard to what is called Yoseikan.