Hundreds of Minamata disease patients and their supporters marched through central Tokyo on Saturday, two days ahead of the 50th anniversary of its official recognition.

Carrying deep-blue sashes symbolizing the Shiranui Sea, the area where the disease broke out, and the salt of the ocean, the participants visited several Minamata disease-related points.

These included the Environment Ministry and the site of the former headquarters of Chisso Corp., the chemical manufacturer which caused the disease by dumping mercury-laced waste water from a synthetic resin factory into rivers in Minamata, Kumamoto Prefecture.