Here is the catalog of Sankosha which was issued in early 1960s. Sankosha was one of a pioneering maker which had made sports bicycle parts and sold them. I don't know well the detail of its history. However, I think it was one of the top makers in Japan from 1950s to early 1960s.
I show the catalog and the leaflet in the below. You would think there is something familiar about design and mechanism. It means domestic bicycle parts maker had started their business from making copy of European products.

The Catalog was offered by Mr. T. N.

3 pages of the general catalog which was folded into two were shown from here. Pantograph type rear derailleur PA was on the front page.
Along with JIS (Japanese industrial standards) mark, the words below were written proudly.
"Recommendation by Japan cycling association. The parts which were used in Olympic."

Derailleur and free-wheel and hub were introduced in the catalog.

Here were derailleur and freewheel. Three kinds of rear derailleur, two kinds of front derailleur, one sifter, and four kinds of freewheel were introduced in this page.

F2 was so-called bamboo type. It was attached to hub shaft (here is a large picture).
The catalog was explaining that the rod type front derailleur was suitable for road racing because it could change the gear quickly. The mechanism was very simple.

PA was a set which was composed of front derailleur, rear derailleur, and sifter. The mechanism around the pantograph of the rear derailleur and the spring was similar to Camapagnolo Gran-sport. The front derailleur was a slide type.
PF was a regular model. We can say it was a copy of Huret Svelto because of similar mechanism and design.
Here were four types of freewheel such as 3/4/5-speed of the flash type and the boss type. Most of cyclists might not know about the flash type.

Two kinds of steel hub and two kinds of aluminum hub were introduced in this page. The quick release hub in the middle was also similar to Campagnolo.

This was the instruction manual of PF rear derailleur. It was folded into two. Right side was the front cover.

Here was detailed explanation about how to attach PF rear derailleur. It really looked like Huret Svelto.

This is an instruction manual of PA rear derailleur. It was folded into two. The right side was the front cover. It was composed of six pages.

Here were the trait and the brief about PA rear derailleur. The third and the fourth were interesting. Mechanism was similar to Campagnolo Gran-sport.

Note;
3. The body is smaller than the present slide-shaft type. You don't need to be anxious about the derailleur even if you tumble down or bump to something.
4. You can reduce a packing volume because the derailleur doesn't have protrusion. It will be a merit for transportation.

Aside from the design, the mechanism was similar to Campagnolo Gran-sport.

There was detailed explanation about how to attach PA rear derailleur as well as the explanation of PF.

This is the exploded view of F1 type. F1 type was regular model, was attached to hub shaft. I had had this set. However I already sold it out in a flea market.

This is the exploded view of slide type front derailleur. The cam moved by wire cable.

The instruction manual of bamboo type derailleur was printed through two pages. It explained how to use derailleur in detail.

I introduced domestic bicycle parts which were made 50 years ago as a sample. The cyclist who had used those parts must be veteran. I suppose that they must have suffered by road condition of those days. However, powerful and easy to use modern parts were made by the effort of such veteran cyclists and makers.