From the mid 1980 there has been an increasing decline in interest in enviromental issues as Japan enacted some of the strictest environmental controls in the world. Why ?

The 1960s saw the growth of civil society movements as industrialisation had been pushed with utter disregard to its effect on health and the environment.
Cadmium poisoning, which led to a painful disease, was an early indicator, followed by mercury poisoning in Minamata in the 1960s and problems caused by air pollution in the early 1970s. Grass-roots pressure groups began to demand recognition of these problems as well as compensation for the victims. Government action and new legal regulations helped to improve conditions. 

Thus from the mid-1980s, there has been an increasing decline in interest in environmental issues as Japan enacted some of the strictest environmental controls in the world.