The first bike I ever owned was a Silk Tokio Katakura. At the time it was pretty slick bike for a 13 year old. It was 10 speed with Shimano 333 derailleurs (not a a 3 speed), alloy pedals, rims, and stem. The model was sport touring or entry level touring bike with front and rear racks, rear panniers and front handle bar bags. The wheels were 26 x 1-1/4 tires and the frame was either 48 or 49 cm. I really loved that bike and regret that it was tossed out of storage when my parents moved from a duplex to a house.
I have never seen another Silk on the street and I suspect that the brand was never officially imported into the US. I bought my bike off a Japanese expatriot. I am guessing that Silks may have been brought back by servicemen or their dependents.
I have found a number of links listing Silks all of them in Japanese. Here are a couple of the more interesting links that I have found.