Katherine Plummer, a longtime Tokyo resident and a leading expert on the history of Edo-era Japanese sea drifters, passed away on March 11 in San Francisco at the age of 91.

Born in Oshkosh, Wisconsin, Plummer taught at the Tokyo YWCA and Kyoritsu Women's University from 1969 to 1998. She wrote many English textbooks while at the YWCA, including "Ranald MacDonald: The First Foreign English Teacher in Japan (1848-49)," which was published in 1982.

As a world traveler who especially favored sea journeys, that book ignited Plummer's interest in the stories of Japanese sea drifters. These were mainly poor Edo-Period fishermen whose boats were carried out to sea by storms and who ended up on distant shores during the period when Japan was officially closed off from the outside world. She painstakingly translated their stories and traveled throughout Japan and the United States retracing their steps, locating their graves and meeting their descendants.

Her first book, "The Shogun's Reluctant Ambassadors: Japanese Sea Drifters," was published in Tokyo in 1984 and revised and republished by the Oregon Historical Society Press in 2000. Her other works include "A Japanese Glimpse at the Outside World 1839-1843: The Travels of Jirokichi in Hawaii, Siberia and Alaska," published in 1991, and "Funaosa Nikki: A Captain's Diary." The latter translation was the first presentation in English of the story of Jukichi, the first recorded case of a Japanese drifter reaching North America.

Even after retiring to the United States, she maintained an interest in Japan, Japanese baseball and sumo, and in emails to friends just a week before her death reported that she was keeping up with Japanese news by reading the online edition of The Japan Times.

As she requested, her ashes will be scattered in the Pacific Ocean between the United States and Japan.