In 1925 she found her mission when a remarkable Japanese evangelist, Toyohiko Kagawa, "called" her to work for him as his English secretary and organizer in America. She had to subordinate herself and take direction from the native leader, revising the usual religious imperialism which held that the native religious leaders practiced an inferior brand of Christianity and could work only under the spiritual guidance and direction of a Western missionary board and dedicated to the proposition of dividing and conquering the Christianity the missionary represented. In Japan the traditional approach had resulted in only a handful of conversions and a certain contempt felt and expressed by the Japanese for a religion which was preached more than practiced.

Toyohiko Kagawa was in no sense traditional. He was born in 1888, the illegitimate son of a geisha and a high-ranking court official. Orphaned at four, he was raised by an unloving stepmother. The first kindness he encountered was from a Christian missionary, and he became a Christian in his teens. Upon doing so, he was disinherited and evicted from his home. He managed, nevertheless, to obtain a Christian education and in 1909, at the age of 21, he embarked on a remarkable period of his life. He went to live for 11 years in the Shinkawa slums of Kobe, working with and helping the poor people of the slums and evolving his life-long commitment to social action. By the time Helen Topping went to work for him he was already well-known for his work in founding churches, settlement houses, cooperatives, labor unions, schools, relief work after the earthquake of 1923, and for the publication of his highly successful first novel Crossing the Death Line.

Miss Topping actually joined Kagawa in Japan in 1927 after founding a support group in Berkeley, California, Kagawa Cooperators, which paid her salary. Kagawa was in the midst of a monumental crusade, the "Kingdom of God Movement," which aimed at converting so significant a portion of Japanese Christianity that the economic and social reforms which he advocated could be implemented. He believed that there could be no social progress without the inward transformation and consecration of the souls of men to the love of God. It was this dual emphasis which attracted so many American supporters but made him a thorn in the side of the established churches.