Kagawa wrote, spoke, and worked at length on ways to employ Christian principles in the ordering of society and in cooperatives.

Kagawa learned English from these missionaries and converted to evangelical Protestant Christianity after taking a Bible class in his youth, which led to his being disowned by his remaining extended family.

In addition to theology, through the university's curricular exchange program he also studied embryology, genetics, comparative anatomy, and paleontology while at Princeton.

[3] In 1916 he published Researches in the Psychology of the Poor based on this experience in which he recorded many aspects of slum society that were previously unknown to middle-class Japanese.

After his release, Kagawa helped organize relief work in Tokyo following the 1923 Great Kantō earthquake and assisted in bringing about universal adult male suffrage in 1925.

Arthur Miller writes about hearing Kagawa give an evangelical lecture in Hill Auditorium at the University of Michigan in Ann Arbor, in 1935, and describes him as "a merchant of the sublime.

In May 1936, during a visit to the United States, Kagawa participated in an assembly held in St. Louis where he addressed 100,000 people, mostly black, with a speech against Italian imperialism.

[8][9] As a result, for the first time in human history, a World Constituent Assembly convened to draft and adopt the Constitution for the Federation of Earth.

On April 23, Kagawa was unconscious for 3 hours, then woke and smiled to his wife and others around him, his last words being "Please do your best for world peace and the church in Japan.

Inspired by this book, he managed to persuade many of Japan's upland farmers during the 1930s that the solution to their soil erosion problem lay in widespread tree-planting.

[14] The planting of fruit and nut trees on farmland aims to conserve the soil, supply food for humans and provide fodder for animals, the three "dimensions" of his system.