It's referred to as Matsunosuke Gin. Toshio and his older brother have hung on to the bloodline that was developed by their father. When it made it's appearance there was much to do in the judging circles about whether those koi should be entered as gin rin hence the more than 3 lines of GR rule.
I found one of toshio's tosai sanke's this year with it, so I had to get it. I;m not sure what it is but I can almost bet that the skin will be good on the koi as it matures. There seems to be a genetic link. I just love that on the koi
and like Mike M I'm not a GR fan ( member the olde brill-creme ads..." a lil dab el do ya.." ) Quess that's how I feel about matsunosuke Gin. The Olson's have a male with Matsunosuke Gin on it, that Mat at Nisei bred that is awsome! As to where the dad got the parents from etc, I have never learned.....just grateful both sons have held on to the genetics.