[1] Seeing Melanesian art while at Nihon University had a big effect on her, as did a visit to Vietnam and Cambodia in 1966.
After graduating in photography, she became a freelance photojournalist,[2] working in west Africa, southeast Asia, and Europe.
[1] Ōishi's work on Vietnam won her the Domon Ken Award.
[2] In both 1982 and 1989 she won the Annual Award from the Photographic Society of Japan.
[2] Her work is in the permanent collection of the Tokyo Metropolitan Museum of Photography.