I'm with you, so curious about the history of gokkun. Are you familiar with the director Rusher MIyoshi? You're certainly familiar with his work...all the JS, ES, NS, BS titles; the BONU series; the PSD series, a number of early ASW titles, MIAD-898 MIGD-748 and the other related videos; and so many others. He is obsessed with gokkun...and he has been in the game for a long time. I found out that he has a bar in Tokyo called Equinox and he is often there along with other industry folks annoucing the schedule on his x.com page. I have this dream of dropping in next time I'm in Tokyo and picking his brain about the topic. In NS-11 with Ayu Sakurai, he gets into explaining some of the history of gokkun to her. (on the .iso version that I have) It's pretty interesting. I think that he would be a treasure trove on info. And who knows who might just stop in at the bar while having a drink there?