The five signs of the decay of an angel are: Tōru, whose purity lies only in his malicious self-satisfaction, is a degenerate parody of the idealised Kiyoaki.
In The Decay of the Angel, the last book of Sea of Fertility tetralogy, Shikeguni Honda, a retired judge, adopts a teenage orphan, Tōru Yasunaga, whom he believes to be a dead schoolfriend's third successive reincarnation.
After turning in the final manuscript for The Decay of the Angel in 1970, writer Yukio Mishima attempted to stage a coup and died by ritual suicide.
He works a 24-hour shift every third day, from an observation tower on the Komagoe shore, built on top of a strawberry farmer's water tank.
Later, that night, Tōru is visited at his post by his friend Kinue, a mad girl who believes that she is incredibly beautiful and that all men are after her.
After midnight, at his house in Hongō, Honda dreams about angels flying over the Miho Pine Grove, which he had visited that day.
In her old age, Keiko is devoted to the study of Japanese culture, but her knowledge is second-hand and superficial, and Honda calls it a "freezer full of vegetables".
They have their picture taken, sticking their heads through holes in a board painted to make them look like Jirōchō and his wife Ōchō, who were bosses of Shimizu Harbour in the 19th century.
In Keiko's hotel room on Nihondaira, Honda explains to her the significance of the moles and tells her the whole story of Kiyoaki's two previous reincarnations.
On 10 August, Tōru becomes aware that he is being investigated by detectives through a story of Kinue's, and later that month he is visited at home by the superintendent, who announces Honda's intention to adopt.
Honda is eager to protect him from premature death and tries to inculcate the cynicism that Kiyoaki, Isao and Ying Chan lacked.
In late November the literature tutor, Furusawa, takes him to a local coffee-house and tells him a political parable about the nature of suicide and authority.
As the demure relationship progresses, Tōru analyses Momoko and, while talking to her in the Kōrakuen Garden a year or so after their first meeting, he decides to make her jealous by acquiring a second girlfriend.
Tōru realises that Honda has guessed that the letter was fake, and that he takes satisfaction in the guile his adopted son displays.
He becomes violent with Honda and intimidates him into getting his way on everything, moving Kinue into a hut at the bottom of the garden, spending money freely and abusing the maids.
On 3 September 1974, Honda is caught spying on couples in the park, and the incident makes the newspapers; Tōru moves to have him declared senile.