Japan has a long history of bicycle manufacturing and while many makers are relatively unknown outside of Japan or had their bicycles branded with other names, the quality of the bicycles they exported through the 1980's stands as some of the greatest eras in bicycle production.

Sheldon Brown said that Miyata never manufactured a bad bicycle and has been in business since 1892... besides producing their own bicycles they also built bicycles for a large number of other companies including (but not limited to) Centurion, Bridgestone, Nishiki, Raleigh, Fuji, Peugeot, and Univega. This might explain why some of these brands are held in such high regard as they were built very well.

Nishiki is an example of a brand that was produced by a number of manufacturers, Kawamura was the original manufacturer and then Giant Bicycle took over production when the yen crashed and most production was moved to Taiwan... as noted Miyata did some work for Nishiki but was not the primary manufacturer.

One of my favourite manufacturers is Kuwahara, they were established in 1918 and like Miyata contracted production to other brands, most notable would have been Schwinn but they had a deep customer base. Their first Kuwahara branded bicycle was their BMX, a field they were held in high regard for and Elliot's BMX in E.T. was a Kuwahara. Kuwahara exported Apollo road and mountain bikes to North America through the 70's bike boom and through the middle of the 1980's their bicycles slowly lost the Apollo name as the Kuwahara name became well recognized. Like Miyata Kuwahara made a wide range of bicycles and quality of their production was very high, they too outsourced production in the late 1980's because of the Yen. Their hand built models from the mid eighties are rather exceptional bicycles.

Bianchi had a large number of bicycles produced in Japan in the 1980's and the Japanese models are often nicer than their Italian counterparts (frame wise)... I am not sure who they had building but their is a good chance it was one of the upper tier companies as the workmanship was very high.

Although they are not seen south of the border as much, Steve Bauer started a bicycle company in the 1980's and when he could not get his bicycles built in Taiwan he went to Japan and the Japanese built frames and forks are very very nice... the finish quality is also very high. Later production quality dropped considerably when production shifted to Taiwan.