Complex sentence: Her father, Ransford Miller, had worked at the American embassy in Tokyo from 1890, while her mother, Lilly Murray (who had arrived in Japan as a missionary in 1888), taught English at the Christian mission.
Split into simpler sentences: Her father, Ransford Miller, had worked at the American embassy in Tokyo from 1890. Her mother, Lilly Murray arrived in Japan as a missionary in 1888 and taught English at the Christian mission.