Greetings from the Academy of S. Gabriel!
You asked about <Dokusai no Gyoja> as a Yamabushi name. You also asked about armory that you described as 'a circular border [that] separates into three peaks at the top, an S shaped river originating between the center and right peaks, with a hut near and above the upper curve of the river'.
Our discussion of the name is based primarily on information supplied by Solveig Throndardottir, our consultant on Japanese names.
There are a few problems with <Dokusai>. The first is technical: it combines a Chinese reading of the first character with a Japanese reading of the second. Such combinations are normally avoided, especially in religious names.
A bigger problem is the actual meaning of the name. The order in which the elements are combined implies that the meaning of <Dokusai> is 'stink of the road'. It is extremely unlikely that a priest would be called 'stinky', which is essentially what this name signifies. For the sake of comparison, here the actual names of some famous Buddhists and their meanings:
<Doh'gen> 'Base of the Way to Enlightenment'
<Nichi'ren> 'Carrier or the Sun'
<Ni'ko> 'Light of the Sun'
<Ik'kyuu> 'First Rest'
Finally, even if there were no problems with <Dokusai>, we doubt that <Dokusai no Gyoja> 'practitioner of Dokusai' follows any recognized Japanese naming practice; it appears to be a description rather than a name.
There are also problems with the proposed armory. First, it probably needs some modification to make it an authentic <mon>. We're not sure from your description just what the border looks like, but it may be a relatively uncommon but standard <kamon> border. If so, only the hut keeps the design from being reasonably authentic.
If you want to register this armory with the SCA College of Arms, however, there are other problems. The College will register armory in a Japanese style, but only if it can be blazoned in standard Western European terms. It's unlikely that your border meets this criterion; if you intend to register the armory, you'll probably have to change it to a standard European border, perhaps a 'bordure indented'. Similarly, the river would probably have to be represented by a 'bend sinister wavy'. It may be quite difficult to modify this design so that it is both registerable and a reasonably authentic <mon>, so you may have to choose between registerability and authenticity.
We hope that this information is useful. If you have any further questions, please don't hesitate to write us.
For the Academy,