As the dramatic climax of The Sea of Fertility, The Decay of the Angel brings together themes that have branched through the three previous novels--the meaning (and decay) of Japan's courtly tradition, the essence and value of Buddhist philosophy, and Mishima's apocalyptic vision of the modern age.
Yukio Mishima's The Decay of the Angel is the final novel in his masterful tetralogy, The Sea of Fertility. It is the last installment of Shigekuni Honda's pursuit of the successive reincarnations of his childhood friend Kiyoaki Matsugae.

It is the late 1960s and Honda, now an aged and wealthy man, once more encounters a person he believes to be a reincarnation of his friend, Kiyoaki -- this time restored to life as a teenage orphan, Tōru. Adopting the boy as his heir, Honda quickly finds that Tōru is a force to be reckoned with. The final novel of this celebrated tetralogy weaves together the dominant themes of the previous three novels in the series: the decay of Japan's courtly tradition; the essence and value of Buddhist philosophy and aesthetics; and, underlying all, Mishima's apocalyptic vision of the modern era.