In 1986 the Takara toy company licensed the Hasbro G.I.Joe brand for release in Japan. It lasted only a year. However, its failure should not be associated with a lack of promotion. Takara relied on it's marketing of the Transformers brand to guide it's push of G.I.Joe. The Sunbow cartoon was dubbed and aired in Japan. Comics were printed, magazine stories run, books distributed and cross-marketed novelty and candy items sold.
Takara had a working relationship with one of the kings of candy toy production, Kabaya. G.I.Joe received two different types of candy toy assortments. The first and smaller of these types was the "G.Ijoe Chocolate: Super Mecha & Character Model" line. This line featured 4 G.I.Joe and Cobra vehicles, each with a figure.
The best of these sets is the Cobra H.I.S.S. tank. The H.I.S.S. came with none other than Cobra Commander himself. The set came package as a unassembled model. The instructions were simple, as was the building of the toy model. Given these are aimed at about the 5-8 year old market, no candy toys are ever very difficult to assemble. When done, you have a small H.I.S.S. with the Commander standing by to give the order to retreat.
In terms of rarity, these things are way up there. The market for candy toy items in Japan is expensive, and expansive. Candy toys can command hundreds of dollars in Japan. Finding these cheap would be best left to buying from U.S. based collectors who may have them for sale.