A powerful miko named Hanyuu is born and treated as a demon because of her horns.
- Hanyuu chooses to bear all the sins of the villagers herself and have her daughter, Ouka kill her with the Onigari no Ryuoh.
- Through sarifice Hanyuu becomes a deity who watches over the area. Deeds she did contributed to the legend and worship of Oyashiro-sama.
- Over time Hanyuu's powers faded until even the Furude's could no longer see her.
- Dr. Takano discovers the Hinamizawa Syndrome and devotes his life researching it.
- Tanashi's parents die and she is put through hell in an orphanage.
- Dr. Takano rescues her and she becomes fascinated with his research
.- Dr. Takano presents his findings to the government but his work is ridiculed.
- Dr. Takano commits suicide.- Tanashi changes her name to Takano and devotes her life to continuing her grandfather's research.
- Takano uses her connections with Koizumi to push forward a project for researching Hinamizawa Syndrome.
- Mion and Shion are born, with Mion being born first. She becomes the heir to the Sonozakis.
- Mion and Shion occasionally swap places. Shion accidentally gets marked with the demon tattoo instead of Mion. Unable to reverse the situation, Shion becomes Mion and Mion becomes Shion.
- Rika is born, as the 8th successive Furude female. She's Oyashiro-sama's reincarnation, allowing her to see Hanyuu.
- Reina moves out of Hinamizawa.
- Government starts a dam project in Hinamizawa.
- Houjos go against the Sonozakis and anger the other citizens of Hinamizawa. Houjous become hated by everyone.
- Akasaka visits Hinamizawa and Rika tells him of her upcoming death.
- Yamainu kidnap the minister's grandson to suspend the dam project.
- The dam manager succumbs to the syndrome and attacks his fellow workers, he is killed in retaliation.
- The 5 workers agree to cut up in the body into 5 parts and keep them hidden.
- A live specimen is needed to advance Hinamizawa Syndrome's research. Takano brings in one of the dam workers suffering from L5.
- The dam manager's mutilated body is found and the 4 other workers are arrested. The manager was like a second-father to Ooishi.
- Ooishi swears to find the person responsible for the manager's death and return the right arm that went missing.
- Rika's dad informs his wife and daughter about Hinamizawa Syndrome and how Rika is the Queen.
- Rika volunteers to be Irie and Takano's guinea pig to save Hinamizawa from the syndrome.- An emergency response plan is set up. So the government can wipe out the villagers in case everyone goes berserk.
- Satoko suffers from the syndrome and isolates herself from everyone but Satoshi and begins to believe her own parents want to kill her.
- Satoshi undergoes heavy stress from having Satoko constantly rely on him. Irie convinces him to join the baseball team he's manager for to help relieve stress.
- Satoko goes with her parents on a vacation and pushes them off a viewing platform.
- Satoko and Satoshi are pushed in the hands of their aunt and uncle. The aunt and uncle abuse Satoko and Satoshi.
- Satoko is brought into the clinic and is discovered to have L5.
- Rika convinces Irie to use the experimental medicine C103 on Satoko.
- Satoko recovers to L3 and is released from the hospital, while maintaining daily injections and weekly visits.
- Oishi tries to interrogate Satoko, believing her parents death is connected to manager's death.
- Rika's parents interfere with the research on her daughter.
- Takano has the Yamainu kill Rika's parents.
- Reina blames herself for her parents divorce. She's begins cutting herself as punishment.
- Reina is almost raped at her old school and snaps, nearly killing them.
- Reina is put on a strong medication.
- Mion starts the club games for Satoko's sake, to help erase her loneliness.
- Reina hears Hanyuu apologizing and believes all her misfortune to be Oyashiro-sama's curse.
- Reina moves back to Hinamizawa and changes her name to Rena.
- Shion falls in love with Satoshi.
- Satoshi is stressed as ever, now hearing Hanyuu's footsteps.
- Satoshi kills her aunt to help Satoko.
- Shion tries to cover up Satoshi's murder and has 3 nails ripped out as punishment.
- Irie picks up Satoshi after he bought a huge bear for Satoko's birthday. Satoshi begins clawing at his throat. Irie takes him to the clinic.
- Mion rips out 3 of her nails too for Shion's sake.
- Rika and Satoko live together with Irie paying for their expenses.
- Mion confronts Oyrou about Satoshi's disappearance.
- Keiichi goes around shooting kids with a bb gun. Until one day he accidentally shoots a little girl in the eye and turns himself in.
- Koizumi passes away and the government loses interest in Hinamizawa Syndrome. The project will be suspended in three years.
- Takano is approached by a mysterious woman, offering her a way to achieve her goal and get back at those who ridiculed Dr. Takano's work.
- Oyrou realizes the hate for the Houjos will go away quicker if new people move in, Sonozakis sell off some land.
- Keiichi's dad tours Hinamizawa and talks with Rika and Hanyuu. This convinces him to move there.
- Keiichi moves to Hinamizawa.