The following version of this book was used to create this study guide: Onda, Riku. The Aosawa Murders. Bitter Lemon Press 2020. English Translating by Alison Watts. (First published in Japanese in 2005 as Eugenia by Kadokawa Corporation.)

The novel is separated into 14 different sections and a prologue, and it includes a wide variety of perspectives and tenses. The Prologue is an interview transcript between Hisako Aosawa and Detective Teru recorded immediately after a mass-poisoning that left 12 people dead and only young Hisako and the housekeeper alive. Hisako says all she can remember about the day is the blue room, the white flower, and how afraid she was.

In “Part One,” an unnamed interviewer has a conversation with Makiko Saiga 30 years after the poisoning. The interviewer only includes Makiko’s words, though Makiko often addresses the interviewer and sometimes asks her questions. However, the interviewer’s words and thoughts are not included. This is a style that continues throughout the novel. In the interview, Makiko says she was ten when her brother came home from the Aosawa’s birthday party and told her to come back with him because one of Mr. Aosawas friends from college had sent soda and sake for everyone to share. When the siblings arrived at their neighbor’s house, they found everyone dead and writhing in the blue dining room. There was a white flower on the table and a strange poem underneath the flower. The police investigated the horrible tragedy, but no leads surfaced until a young man with a history of mental illness was found in his apartment with a suicide note confessing to the crime. However, many suspected he did not work alone. When Makiko went to college, she researched the crime for her senior thesis and ended up publishing what came to be a bestselling book. Makiko tells the interviewer that she always found Hisako’s first interview strange since Hisako, who was in middle school at the time of the crime, had been blinded as a small child in a swing-set accident. Hisako described colors in her interview, and this makes Makiko suspicious of her. If ten people are at a party and nine die, Makiko says, then the obvious culprit is the survivor.

In “Part Two,” Makiko’s research assistant is interviewed. He says that he was surprised, after the book came out, to note that many inconsistencies were in the book. He wonders if Makiko meant them as a message to someone.

In “Part Three,” an excerpt from Makiko’s book is presented. Makiko writes about herself in the third-person past as she details the morning of the poisoning. She writes that Hisako deliberately told her not to go to the party that day because she had a bad feeling.

In “Part Four,” the housekeeper’s daughter is interviewed. The housekeeper’s daughter says she always hated the Aosawa’s house. One day, she had gone upstairs and seen a small blue room that contained nothing but a white flower on a shelf. Her mother told her it was Mrs. Aosawa’s prayer room and acted strange about it.

In “Part Five,” Detective Teru is described in the third-person past. He had always been very intuitive. He knew that Hisako was responsible for the poisoning as soon as he first saw her.

In “Part Six,” Makiko’s older brother is interviewed. He says his sister was always good at pretending to be other people. Once, after the murders, she had put a mildly poisonous flower in their mother’s stew so she could see what it felt like to poison someone.

In “Part Seven,” a seemingly omniscient narrator (who might arguably be the anonymous interviewer) zooms in on a young master who runs into the delivery driver several times, including near a temple playing with a group of children.

In “Part Eight,” a young boy who lived near the delivery driver is interviewed. He says that the delivery driver used to help tutor him with his science. Before the murders, the delivery driver started to act strange. He said he was talking to flowers. One day, he was carrying a strip of paper with two addresses written down in girly handwriting.

In “Part Nine,” the narrator and point of view are intentionally impossible to pin down, but through context-clues we gather that Hisako and a man sit on a bench and talk to one another about wanting to be alone in a country of their own. Hisako also talks to a group of children about playing with fireworks.

In “Part Ten,” journal entries from Makiko's time writing her book are presented, and then the editor of her book is interviewed. The editor says Makiko was never very interested in the outcome of her book. She also says that a used bookstore burned down after the book came out.

In “Part 11,” the detective is interviewed. He says he realized that he needed to find the slip of paper with the two addresses on it to prove that the delivery driver had not worked alone. However, by the time he realized that Makiko had described the physical reality of their small town with precise detail except for the used bookstores in order to indicate that the delivery driver must have put the slip between the pages of a book and sold his books to the used bookstore that specialized in science titles, it was too late. The bookstore had been burned down.

In “Part 12,” a series of documents is presented. Makiko dies on a bench from heatstroke. A citizen’s group protests the destruction of the Aosawa’s house, despite Hisako’s wishes. Hisako is living overseas, but she prepares to come back to Japan to settle matters. A letter from Makiko’s younger brother to an anonymous friend reveals that Junji knew about the poisoning before it happened and did not say anything.

In “Part 13,” the friend of Junji reveals herself as the anonymous interviewer and potential narrator of the entire novel. After getting his letter, she decided to investigate the case again. She meets Hisako and Hisako tells her that everything was just an accident. However, in a third-person-past section, we see Hisako wake up on the day of the poisoning excited for what is to come.

In “Part 14,” the section is told in third-person-present with a focus on Makiko, but switches to a third-person-past on Hisako at the end. The section follows Makiko as she meets up with Hisako for the last time on a bench painted with red flowers. Hisako confesses she used to meet the delivery driver here and speak with him. It is revealed that Hisako’s mother was abusive and likely blinded her. Hisako had been terrorized in her mother’s blue prayer room with the white flower. It is suggested, without being stated, that Hisako committed the murders to stop the abuse.