In 1973, Japanese courts pinned responsibility for the horrific Minamata disease on the Chisso Corporation, a Minamata-based chemical company. Some 20 years before, dead fish had started to appear in the Yatsushiro Bay, the first sign that something was wrong. Then, crows began dropping out of the sky. Next, the cats of Minamata, on the island of Kyushu, became blind and palsied, whirling themselves grotesquely about before hurling themselves into the bay. When the cats disappeared, rats proliferated, but the "dancing disease" soon claimed the rats as well. Finaaly, the mysterious plague struck at humans as well, killing more than a thousand while blinding and crippling countless more.

By 1963, it had been confirmed that Minamata Disease was not a disease at all but was actually mercury poisoning caused by eating contaminated fish. Scientists from the nearby Kumamoto University soon traced the source of the contamination: among the 460 tons of pollutants which the Chisso had dumped into the bay over the years were 27 tons of methyl mercury. (Later, a Chisso company doctor said that the corporation had known of the problem since 1959 but had kept dumping anyway.) However, the government did not officially acknowledge the cause until 1969.

Chisso eventually paid out more than $600 million to some 2,000 victims in a settlement, but problems such as strict certification rules died up action for over two decades. Meanwhile, thousands have sued the government for negligence in its slow initial response to the disaster. To this day a formal conclusion has not been achieved.