Nope. See https://www.youtube.com/watch?v=Rpq42dxj1po
. Although, I dunno, I guess you could turn it into a choke? But I think there's a judo technique of the same name that's a choke with the gi?
I might be able to find one, if I had the time to scour through Youtube, but there's a good chance I could look all day and not find it. It was ryotetori sumiotoshi, but not on the side that you'd probably expect, and ended in katagatame. Hard to describe, fun to do.
I don't know "rokukyo". We have rokyo, but I don't know anything called "rokukyo". Got a vid?
Katagatame, the way I know it, is one of the major osaekomi, or hold downs, in judo. It can turn into a choke, most people do it that way, but technically its a shoulder/arm hold down like a sankakujime almost. From the video you posted of Mr. Chiba - is katagatame the pin at the end or the whole movement?
Our kihon sumiotoshi is actually on the outside of uke's elbow...though the inside, or kiriude, is acceptable as well, for us. So long as our direction of movement is to a corner on an oblique angle away from uke's base of support, its all good for us.
Been doing some research into rokyo. From what I gather on Youtube it just looks like we lump both movements together as gokyo. Our kihon version of gokyo is like a variation of wakigatame, which uses nage's armpit as a leverage point. But if we keep uke's arm out away from us, we still call it gokyo, so long as its a 'mixed grip' where nage's grabbing uke's wrist with a palm up grip, and creating the opposing vertical pressure differentiating it from, say, ikkyo.