The Aosawa Murders is the first crime novel written by Riku Onda and was published in Japan in 2005. Bitter Lemon Press later published an English translation in 2020.
The novel focuses on a 1973 mass poisoning case set in seaside city K—. At a birthday celebration for the influential Aosawa family, seventeen people died from poisoning after drinking sake and soft drinks.
Onda's writing style is classified as shin honkaku, a "new orthodox" form of Japanese detective fiction, and is structured to focus on three converging timelines.
Onda drew inspiration for the novel after listening to Michel Petrucciani's song Eugenia. It also references the Teigin Incident, a real case of mass cyanide poisoning in Japan that occurred in 1948.
The reception of the novel was well received, landing on top 100 notable books of 2020 by The New York Times. She won the Best Novel for Mystery Writers of Japan Award in 2006.
Summary
The Aosawa family is a prominent family within the city of K–. As they celebrate a multi-generational birthday party, that admiration is sullied when an unnamed man presents the attendants with sake and soft drinks as a gift. This resulted in the death of 17 people: family and friends who had gathered for the party. The Aosawa housekeeper miraculously survives, but the survivor that everyone focuses on is Hisako Aosawa, the beautiful, blind daughter and only survivor from the Aosawa family. Makiko Saiga, one of her admirers, discovers the crime along with her older brothers. Makiko, being so affected by the mass poisoning, wrote the novel The Forgotten Festival which was inspired by the event.
An unnamed narrator interviews Makiko about her thoughts on the murders. Makiko reveals that her novel started off as a university thesis but then got picked up by a publisher. She explains that she wanted to figure out something by publishing the book, but after its release, she lost interest in it. At the end of the interview, the narrator asks her about the real culprit. Makiko comments that the answer is easy–when all but one die in a household, it is the survivor.
In an interview with Makiko's assistant, he reveals how dedicated Makiko was to the project, but also how odd she acted doing research. In her interviews, she unknowingly changed personas depending on who she was talking to. This oddity is magnified by her fixation on Hisako herself. An excerpt from Makiko's novel makes this obsession apparent. Hisako's character asks Makiko’s character not to come to her house on the day of the birthday party. Describing Hisako in detail, Saiga creates a picture of Hisako as "seeing" the world differently due to being blind. In an interview with the housekeeper’s daughter, she recounts that she once saw Hisako swinging with a big, eerie smile, unnerving her. In a change of interviewees, the detective recounts his experience. He is also suspicious of Hisako and knew at first glance that she was guilty of the murders. The narrative is altered again with the interview of Sei-ichi, Makiko Saiga's eldest brother. In an off-beat manner, he asserts that the Aosawas had it coming due to their fame.
In another interview, a young master talks of a man who turns out to be the nameless man that delivered the poisoned drinks to the Aosawas. Ultimately, he was arrested and charged. However, the young master is not convinced of this outcome. The young man was private and interested in Buddhism, particularly the third eye, a concept of seeing past the ordinary world. In a perspective change, the unnamed narrator interviews someone who was a kid at the time of the murders and was friendly with the young man to the point of calling him "Big Brother". He admits Big Brother was troubled, and oftentimes heard a voice he described as a white flower. He does not believe that Big Brother committed the act alone. Many clues are left unsolved, and the people of K— think the case was closed with an insufficient resolution. A poem called "Eugenia" was left by the perpetrator, but no one can decipher its meaning. The man called Big Brother delivered the drink but had no motive to kill, and Hisako Aosawa witnessed the entirety of the poisoning but cannot give any tangible details. Decades later there is still a search for the truth among long-held beliefs and the sour feelings of the people living in the seaside city of K—.