This page attempts to compile a chronological timeline of pre-June 1983 events in Higurashi no Naku Koro ni . Information is primarily based off of Matsuribayashi, especially the Connecting Fragments section.
For a timeline with included events from console ports, see this page.
This article or section contains untagged major spoilers for all of the original Higurashi no Naku Koro ni, possibly including the console-exclusive arcs. Readers who have not completed the main story are advised not to proceed further.
- Approximately 1000 years ago, Hanyuu's race arrive to Onigafuchi Village. Origin and earliest possible spread of Hinamizawa Syndrome.
- Hanyuu is sacrificed to quell the villagers' paranoia. Faith and religion built around Oyashiro-sama begins.
- Onigafuchi transforms into Hinamizawa in the Meiji Era.
- July 7, 1937: a soldier from Hinamizawa who developed terminal symptoms of Hinamizawa Syndrome fires upon Chinese forces, triggering the Marco Polo Bridge Incident and consequently the Second Sino-Japanese War.
- Several soldiers from Hinamizawa enlisted into the Kwantung Army begin exhibiting bizarre behavior. Hifumi Takano, an army physician, discovers this and begins research into the Hinamizawa Syndrome parasite.
- Miyoko Tanashi's parents die and she is sent to an orphanage, later adopted by Hifumi. Miyoko changes her name to Miyo Takano in honor of him.
- Hifumi presents a report of his findings into Hinamizawa Syndrome but his research is dismissed as nonsense. The young Takano becomes determined to prove his research legitimate.
Late 1960s-Early 1970s
- Akane Sonozaki is disowned from the Sonozaki family.
- Mion Sonozaki and Shion Sonozaki are born as twins.
- Self-Defense Force forms the Alphabet Project and shows interest in Hinamizawa Syndrome research, giving funding and support to Takano. Koizumi also gives Takano his support.
- Kyousuke Irie is brought onto the research project due to his knowledge. The Irie Institute organization is formed to facilitate research, with Irie the puppet leader while Takano acts behind the scenes. Jirou Tomitake is appointed as auditor for the project and Tetsurou Okonogi, leader of the Mountain Dogs is introduced as a supportive military unit.
- Mion and Shion switch. The younger sister obtains the demon tattoo and is forced to become Mion while the older sister becomes Shion.
- Irie Clinic begins construction in Hinamizawa, completed by next spring.
- Hinamizawa Dam Project begins. The villagers begin protesting while Tokyo starts working to stop the project.
- The Houjou family becomes ostracized by the village due to their support of the dam.
- Research suggests that Rika Furude is the "queen carrier" of the Hinamizawa Syndrome parasites; her presence keeps the villagers from developing terminal symptoms and going insane. The Furude family is told the existence of the parasites and are asked to cooperate with the clinic for research.
- To stop the dam project, the Mountain Dogs capture the Minister of Construction's son and send a ransom note. Mamoru Akasaka's division begins investigation. In some Fragments, Akasaka returns to Tokyo after heeding Rika's warning and prevents his wife Yukie from dying. Otherwise, he remains in Hinamizawa for the investigation.
- The dam construction manager is killed and dismembered by other construction workers. The ringleader of the incident becomes a terminal patient and is later captured by the Irie Clinic to be dissected for research.
- Takano drafts Emergency Manual 34, a plan to exterminate the village should Rika and the queen carrier die. Equipment is stored in Yagouchi in preparation for such an event.
- Satoko Houjou kills her parents by pushing them off of a cliff in Shirakawa Park. She and her brother Satoshi are taken to live with their aunt and uncle after the incident.
- Satoko is revealed to be a terminal patient. Plans are made to dissect her, but they are later retracted in favor of testing the new medicine C103 on her, meant to pull her out of the terminal stage.
- The Mountain Dogs throw off police investigation by disposing of the wife's body from the Shirakawa incident. The possibility of Oyashiro-sama's curse being an annual occurrence grows among the villagers.
- The Furude family offers their consent for Rika to be examined.
- Takano develops H170, a drug meant to force a person into terminal stages of Hinamizawa Syndrome.
- C117 is developed.
- Koizumi dies, causing a power imbalance in Tokyo. Plans are made to slowly reduce the budget of the Irie Clinic and stray away from researching Hinamizawa Syndrome for military applications.
- Shion is sent to St. Lucia Academy.
- Rika's mother grows suspicious of the clinic and retracts consent for Rika to be examined. Rika's father also retracts consent and demands to see results in three months. To prevent research from being stopped, the father is poisoned and killed by the Mountain Dogs while the wife is captured and dissected for more insight into the queen carrier parasite. The villagers believe their deaths to be the third year of the curse.
- Rena's family move out of Hinamizawa and her parents divorce. Rena indulges in self-harm and almost commits suicide but is stopped through Hanyuu's intervention. She is given medicine later.
- Shion escapes from St. Lucia and moves to Okinomiya.
- Incident in Ibaraki where Rena assaults several students and destroys property. She is submitted for psychiatric evaluation, with Rena and her father moving back to Hinamizawa soon after.
- Mion creates an after-school games club.
- Satoshi kills his aunt on the night of Watanagashi. Several days later, he buys a gift for Satoko and calls Irie for help. Irie takes him to the clinic and puts him into intensive care after seeing he's a terminal patient.
- The Irie Clinic is given three years to wrap up research of Hinamizawa Syndrome. Research notes for H170 are destroyed by Irie upon request by higher-ups, however Takano keeps one last sample.
- Maebara mansion finishes construction and Keiichi Maebara moves to Hinamizawa.
- Nomura convinces Takano to prove her research as legitimate.
- This website for the Higurashi light novel suggests that Miyoko escaped the orphanage in 1957.
- Onikakushi Day 9-2 says the dam project started seven to eight years ago, placing its start year as 1975-1976.
- Meakashi Day 2 has Shion saying she attended St. Lucia for about two years and needed to fill in the missing info from that time. She knew about the second year curse victims but not the third.
- Onikakushi Day 2