The film is grounded in the harrowing true events of the Minamata tragedy, officially "discovered" in 1956. The neurological disease, caused by ingesting mercury-laden seafood, resulted in:
: Victims suffered from numbness, loss of motor control (ataxia), blurred vision, and in many cases, convulsions and death.
: The most heartbreaking cases involved children born with the disease after being poisoned in utero—a discovery that challenged medical beliefs at the time.