The Great Hinamizawa Disaster (雛見沢大災害, Hinamizawa Daisaigai) or GHD refers to the tragedy that ultimately destroys all of Hinamizawa in most of the arcs. This disaster always occurs if Rika has been killed by Takano's hands, and is first recounted in Tatarigoroshi-hen. In arcs where Rika is killed by Shion or commits suicide such as in Watanagashi-hen the disaster does not occur.

The Official Story Edit

The official version of the events per the reports of members of the Japan Special Defense Forces (JSDF) is as follows: In the early morning following the hostage situation in Tsumihoroboshi-hen, volcanic gas composed of hydrogen sulfide and carbon dioxide was released from Onigafuchi Swamp. The gas spread through the village killing everyone while they slept. The JSDF removed the bodies, quarantined the area for almost 20 years, and covered Onigafuchi Swamp with thick concrete. Prior to the disaster, Irie Kyōsuke committed suicide by poison while Furude Rika was found to have been a victim of a ritual murder.

Popular Theories Edit

In the aftermath of the disaster a number of theories arose:

  • "I'm Not Sayings it's Aliens, but it's Aliens": One popular theory claims a government conspiracy to cover up an alien bio-terrorist attack. They cite multiple points to support this theory: experts claim that filling the swamp with concrete will not stop future gas releases; hydrogen sulfide should have corroded metal and caused significant environmental damage in the town but there is no evidence of this; and the SDF soldiers who worked in the area after the disaster received frequent blood tests, which the conspiracy theorists cite as evidence of a bio-terrorist attack. The primary support for the alien theory comes from Document No. 34 and the words of Ryūgū Rena from the night prior to the incident.


The deaths of Tomitake Jirō, Irie Kyōsuke, Furude Rika and the entire village ultimately derive from a plot by Takano Miyo to validate the theories of her adopted grandfather Takano Hifumi: Tomitake is injected with H173 and dumped on the side of a road to succumb to an induced end-stage Hinamizawa Syndrome; Irie is poisoned with narcotics; and Rika is ritually disemboweled at the Furude Shrine. To affirm her grandfather's theories of how Rika's death will induce a widespread errupting of the Hinamizawa Syndrome amongst the Hinamizawa villagers, she initiates the plan to exterminate the town to present the spread outside of the area.