This humble, but stylish, document is a set of instructions for this 'SunTour Svelto'. The exploded diagram clearly shows a derailleur with a cable adjuster - which is something that I have also seen on Huret Sveltos made in France - but it is something that I have yet to see in a Huret catalogue.
Hideki Sasaki, in the first volume of his SunTour 'Derailleurs of The World' books, shows a SunTour Svelto that is clearly branded 'Sun Tour' on the top parallelogram plate. He says that it is has 'Maeda Iron Works Japan' on the lower parallelogram plate. If I am understanding the Japanese text correctly he may also say that initially SunTour assembled the Sveltos from imported parts, but later manufactured the parts in Japan. The derailleur that he depicts has a cable adjuster and a black hanger plate. Finally he suggests that SunTour produced the 'SunTour Svelto' until 1969 - well into the period when they were marketing their own, vastly superior, designs.