Project Yamainu (Japanese: Mountain Hound) was code name for a biological weapons project covertly undertaken during the the late 2040s by the Japanese military for use against the Chinese military. The Yamainu virus itself is a neurotropic single-stranded RNA virus vaguely similar to the Lyssavirus (rabies virus), but genetically engineered through gene splicing to create a highly virulent biological weapon. Most notably, unlike the rabies virus, which is transmitted by direct contact, typically bites, the Yamainu virus was specifically designed as an airborne virus, and has been specifically modified to resist conventional treatment methods.


The virus has an incubation period of 12 hours to 3 days, much shorter than the rabies virus, after which symptoms appear. The first symptoms are as not specific as fever and headache, however, these may progress in a matter of hours into paranoia, terror, and audiovisual hallucinations. These hallucinations may be complex in nature, but almost always lead to violent behavior. In many case, the subject retains intelligence sufficient to operate a firearm for periods of up to twelve hours after onset of the most extreme symptoms. This is by design, intended to cause chaos in enemy ranks by causing mass friendly fire incidents as infected soldiers attack each other. After a period of about no more than ten days, the host of the virus will expire from inflammation of the brain, however, in practice, those expose to the virus rarely suffer mortality from the symptoms, but rather, are more likely to fall victim to violence at the hands of other infected.

Planned DeploymentEdit

The Yamainu virus was intended to be aerially delivered, typically by a missile, into target areas, such as enemy troop concentrations and cities, at which point the infected would become violent and attack each other. In this sense, the tactical use of the virus can be considered similar to the later US HallucinoGen gas, but on a much large scale. Given the many unknown factors, such as the period of time in which the virus would remain a threat after an area is exposed, the Yamainu virus was primarily intend to be deployed using long-range ballistic missiles to cities, military base, and other targets in the Chinese mainland. The largest warheads designed were projected to contain enough of the virus to infect an area the size of a large city. One such weapon was slated to be aimed at Beijing and, once the existence of the weapon was declassified, would be used as a deterrent similar to nuclear weapons, and, in the event of a Chinese attack, as a first strike intended to eliminate the upper echelons of the Chinese government and military, throwing the invading forces into chaos. Use of the Yamainu virus on Japanese soil was only to be done as a last resort in case they were facing a massive Chinese invasion that could not be halted by conventional means.


Development started on the Yamainu virus in 2041, under the leadership of Dr. Mio Tanashi, one of the leading experts in virology and genetic engineering in the world. Tanashi was placed in charge of a top secret research facility in the mountains west of Shirakawa, where she was placed in charge of development of the virus. Many of the specific records the development of the virus were in the chaos surrounding destroyed in the Shirakawa incident in 2050, however, it is generally considered to be fact that unethical research methods, specifically the use of condemned prisoners and, in some case, kidnapped homeless and other civilians that "wouldn't be missed" as test subjects. It is unknown exactly how many people were killed in the development of the Yamainu virus. In 2048, after many grisly experiments, Tanashi's team finally engineered a virus to specifications of the Japan Self Defense Forces, however, as of the outbreak of the Third Sino-Japanese War later that year, the missiles intend to deploy the virus had not been completed. For this reason, the weapon was never used in the war.

Shirakawa IncidentEdit

The Shirakawa incident occurred on January 13th, 2050, about two weeks after the signing of the Treaty of Kyoto, which placed Japan under military occupation. Upon the signing of the treaty, Tanashi received orders to shut down all weapons development activities and destroy all samples of the virus in a biohazard incinerator. Instead, Tanashi, along with a group of facility scientists and guards with nationalist Japanese sympathies mutinied, intending to use the virus in terrorist attack, hoping to cause enough damage to force the Chinese to cancel the operation. While outwardly Tanashi appealed to nationalist sympathies, it was rumored that her mutiny was at least in part a desire to see the virus, which she was rumored to sometimes call "her baby" used, regardless of the circumstance.

About two weeks after receiving word of the mutiny, Chinese People's Liberation Army Forces were deployed to seize the facility by force. As they closed in on the facility, the mutineers rigged the site with explosives. At roughly 10:45 AM local time, Tanashi detonated the bomb, according to some rumors, pressing the detonator herself, the last words out of her mouth being a maniacal laugh.

The detonation destroyed the facility, including a large vat containing samples of the virus. The explosion released the virus into the atmosphere. The Chinese forces, who were not aware of the precise nature of the facility, were caught without adequate protective equipment and expose to the virus, along with numerous civilians in the area. Within twelve hours of the explosion, symptoms managed to manifest, with Chinese soldiers opening fire on their comrades and civilians. At the same time, civilians in the area flew into a rage and violently attack each other, though most of the less well-armed civilians were easily cut down by the infected Chinese troops. With 24 hours of the explosion, the area had been practically depopulated. The few that survived the initial bloodbath expired from the disease within ten days. The total death toll was 3472 people, including both Japanese civilians and Chinese military personnel.

Since then, the area around the facility and the village of Shirakawa has been a placed under military quarantine. While it is officially uninhabited, rumors persisted of a few survivors, apparently immune to the disease, living in the ruins of Shirakawa.

Post-Great WarEdit

After the Great War, the few immune survivors of the incident gradually multiplied, and by 2100, virus levels had declines to the point that it was safe for non-immunes to enter the former quarantine zone. As the original causes of the incident were forgotten, they were replaced with stories of the supernatural. Specifically, the residents believe that the crater where the remains of the facility are located is an entrance to the underworld, and that, one day, vengeful spirits rose from the underworld, possessing much of the population and forcing them to slaughter each other. While the residents of Shirakawa will trade with outsiders, they are extremely insular and mistrusting of those not in their community, and insist that traders not stay longer than they need to trade.

For there part, some outsiders are similarly mistrustful of the Shirakawa residents, accusing them of being the culprits for mysterious disapperances in the area. Some even have claimed to have found bodies that appeared to have been ritually tortured and murders, or even witness such macabre rituals, though these more outlandish reports are generally disregarded by most people.

Behind the ScenesEdit

The Yamainu virus is obviously based on the Hinamizawa Syndrome of the anime Higurashi no Naku Koro ni, and Shirakawa is the real-life village on which Hinamizawa, the fictional Japanese town in the anime is based on. This article was partially inspired when the author notice a formerly active user who name is a direct reference to the series.

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