In 1959, Itaru was sent to Prague, Czechoslovakia as an editor of The Problems on Peace and Socialism, an international communist party magazine and his family accompanied him.
Yonehara returned to Japan in 1964, and after graduation from high school, attended the Tokyo University of Foreign Studies, majoring in the Russian language.
With the demise and the collapse of the Soviet Union, her services were much in demand by the news agencies, television and also by the Japanese government, and she was also requested to assist during the visit of Russian President Boris Yeltsin to Japan in 1990.
In 2001 she received the Sōichi Ōya Non-fiction Prize (大宅壮一ノンフィクション賞, Ōya Sōichi Non-fikushon Shō) for The Deep Red Truth of Anya the Liar (嘘つきアーニャの真っ赤な真実, Uso-tsuki Ānya no Makka na Shinjitsu) (ISBN 978-4-04-883681-4) about the search for her classmates at Prague after the collapse of the Soviet Bloc.
Her hobbies included the Japanese word play (駄洒落, dajare), sex-themed jokes (下ネタ, shimoneta), and she kept numerous dogs and cats.