"The Box Man" is a surreal narrative about a man who chooses to live as a homeless individual, inside a box, in Tokyo. The protagonist, a former doctor, narrates his experiences and observations from within the box, and the narrative often blurs the line between reality and hallucination. The book is a philosophical exploration of identity, anonymity, and the nature of existence, challenging the reader's perception of what it means to be an individual in society.

The novel explores the aftermath of a failed doomsday cult in Japan, led by two men who had prophesied an apocalypse that never occurred. After their prophecy fails, they attempt to disband the cult but struggle as their followers resist and violence ensues. The leaders try to rebuild their lives amidst the chaos, grappling with their guilt and the consequences of their actions. The book is a deep exploration of faith, redemption, and the power of belief.