When her American husband, Greg Davis, succumbed to liver cancer in May 2003 at the age of 54, Masako Sakata was seized with suspicion his death was caused by Agent Orange, which he had been exposed to in Vietnam during his three years of military service through 1970.

Five months later, Sakata was in Maine to attend a two-week videography course, with the secret aim of shooting a documentary film on the toxic chemical.

"I wanted to examine if his fatal disease was really connected with Agent Orange, or, in other words, I needed to do something to get over the sorrow caused by Greg's death," said Sakata, now 60.