Why Are the Japanese Non-Religious?: Japanese Spirituality: Being Non-Religious in a Religious Culture, translated here for the first time in English, was first published in Japan in 1996. It has also been translated into Korean and German. Author Toshimaro Ama examines the concept of mushukyo, or lack of specific religious beliefs. According to Ama, the Japanese generally lack an understanding of or desire to commit to a particular organized religion, oftentimes fusing Shinto, Christianity, and Buddhism into a hybrid form of spirituality.

The book classifies Japanese religion into "revealed," or organized (i.e. Buddhism or Confucianism), and "natural," or folklore based. It explains how folklore and culture have been integrated into the Japanese religious mind, examines governmental influence over the development of Japanese religion, and introduces several attempts to restore authentic spirituality. The book, which has sold more than 100,000 copies, is widely popular among students of Japanese culture and ethnicity as well as lay readers desiring to learn more about Japanese religious identity.