Satoko Kitahara was born on 22 August 1929 in Tokyo, into an aristocratic family descended from samurai and Shintō priests. As a youth, she studied pharmacy and during World War II worked in an airplane factory—where she contracted tuberculosis—and gradually became disillusioned with the nationalistic ideology of her time as she learned of wartime atrocities. After the war she drifted spiritually until one day she entered a Catholic church and was deeply moved by a statue of Mary, which led her to pursue catechesis and, in October 1949, to be baptized and take the name Elisabeth (later also Maria).

Following her conversion, Satoko longed to enter religious life, even studying Spanish in hope of joining the Mercedarian Sisters, but her fragile health prevented her from doing so. Instead, she responded to a different call: she met the Polish Franciscan Brother Zeno Żebrowski, who was ministering to Tokyo’s poorest through a rag-picker settlement known as Ants Town (Arinomachi), and she joined him in caring for the outcasts—especially children—teaching them, supporting them, and eventually living among them, renouncing her comforts to share their hardships.

Despite declining health, she remained steadfast in her service and spiritual witness. On 23 January 1958 she died of tuberculosis at age 28.