The Sea of Fertility chronicles the cyclical nature of existence and the pursuit of reincarnation across four distinct historical eras in twentieth-century Japan. The narrative follows the life of Shigekuni Honda, who witnesses the repeated manifestations of a soul he believes to be his deceased childhood friend, Kiyoaki Matsugae. As Honda ages from a young law student into a wealthy, elderly judge, he attempts to track and influence these incarnations, facing the logical constraints of Buddhist philosophy and the shifting political landscape of a modernizing nation. The work utilizes a multi-generational framework to examine the tension between traditional aristocratic values and the encroaching influence of Western modernity.

Readers and critics frequently identify this tetralogy as a monumental achievement in twentieth-century literature, noting its immense philosophical depth and stylistic precision. Discussion often centers on the evolution of Honda as a witness to history and the way the narrative mirrors the author's own obsession with the intersection of life and death. Many highlight the stark contrast between the lush, romantic prose of the first volume and the detached, clinical tone of the final installment. The work is widely regarded as a complex meditation on the nature of reality, with scholars often debating the validity of the reincarnation cycle within the text. Readers should be prepared for a dense, intellectual experience that demands patience and careful attention to the shifting thematic focus across the four volumes.