“No, Mr. Honda, I have forgotten none of the blessings that were mine in the other world. But I fear I have never heard the name Kiyoaki Matsugae. Don’t you suppose, Mr. Honda, that there never was such a person?”
The story jumps to the year 1970 and focuses on two main characters. Honda is now retired and alone in the latest stage of his life. His wife Rié has died some years before, and he often travels alone or with his good friend Keiko. One day, during one of his trips, he is attracted by the observation tower of the Shimizu harbor. Tōru Yasunaga is an orphaned 16-year-old boy working on the observation tower as a signalman, observing and communicating with the ship at the horizon. He is good at his job and seems content with his life and his friend Kinue, a mad girl who believes to be beautiful and has the constant impression that all men are after her. The two characters meet quite soon in the book because Honda, attracted by the observation tower, decides to visit it with Keiko. At that moment, Tōru is about to finish his shift as a signalman and is wearing a loose undershirt showing both his sides. Honda immediately spots the three moles on his left side, identical in size and position to the ones of Kiyoaki, Honda’s dearest friend who died at the age of twenty. Honda is stunned by this vision and, while driving back home, confides the whole story of Kiyoaki’s reincarnation, and the meaning of the three moles, to Keiko. He also announces that he intends to adopt Tōru. Tōru seems quite indifferent to Honda’s decision to adopt him but finally accepts with the feeble hope that he will, one day, inherit Honda’s wealth. Once he officially moved in with Honda, Tōru starts receiving lessons in table manners, social skills, and general knowledge. Honda is well-intentioned to protect Tōru from his premature death, which is expected on his twentieth birthday, following what happened to Kiyoaki, Isao, and Ying Chan. However, Tōru is not an easy person, often driven by despise and cruel behaviors. His relationship with Honda is far from being idyllic. Tōru starts behaving violently towards Honda, who is becoming fragile and vulnerable due to his age. Tōru’s exploiting behaviors culminate when he starts abusing the maids, invites his friend Kinue to move in, and they start spending all of Honda’s money. Eventually, after a lousy incident, which makes it to the newspaper, Tōru manages to have Honda declared senile and to take over his possessions completely. It is when Tōru seems to have found his place in Honda’s life that he discovers from Keiko the whole reason why Honda has decided to adopt him. He understands that he must die at the age of twenty; otherwise, he will be deemed a fraud. As that prophetic day approaches, Tōru tries to kill himself with methanol, failing and remaining blind from the incident. At this point, Tōru and Honda conduct two completely separate lives: Tōru becomes depressed and spends his days in a lethargic way; Honda cuts off his relationship with Keiko after the betrayal and is afflicted by pain. One day, Honda decides to visit the Gesshū Temple for the first time since Kiyoaki’s death sixty years before. There, he asks for Satoko, now the temple's Abbess, intending to remember the old days with Kiyoaki for the last time. Surprisingly, Satoko has no memory of Kiyoaki. The book concludes with Honda’s startling thoughts: “But if there was no Kiyoaki from the beginning, then there was no Isao. There was no Ying Chan, and who knows, perhaps there has been no I.”
In this last book, Tōru represents the final degenerated version of Kiyoaki’s presumed reincarnation. Honda’s rationality is now completely obfuscated by his desperate intent to save Tōru from dying at the age of twenty. In pursuing this symbolic gesture, Honda embarrassed himself personally and professionally with the unsettling final revelation that all this might have been for nothing. Yukio Mishima finished writing the last book of his magnificent tetralogy Sea of Fertility on the 25th of November 1970 and committed seppuku the following day, an extreme gesture to end this grand literary work and his existence.