Symptoms including hallucinations, particularly hearing the footsteps of an imaginary person behind them (believed by the villagers to be Oyashiro-sama), a propensity towards extreme violence, and delusional parasitosis, the delusion that one's body is infested with parasites on or under the skin, and formication, the sensation of insect-like creatures crawling on or underneath (In the case of Hinamizawa syndrome).

The disease often results in suicide, typically by exsanguination associated clawing open a major blood vessel such as ones in the neck, as a result of an attempt to remove the delusional parasites from one's body.

The military has made attempts to weaponize the Hinamizawa Syndrome. for the purpose of this wiki Takano Miyo use a syringe filled with Hinamizawa Syndrome as a weapon.

Takano Miyo was developing H-170, a drug designed to induce the L5 symptoms onto an infected person. Tokyo" is an organization responsible for the Alphabet Project a programe to weaponize the syndrome. In her game apperence Miyo some times use what appears to be a gas form of the syndrome has a weapon.

According to Dr. Takano's research in Matsuribayashi-hen, Hinamizawa Syndrome has five different stages, ranging from L1 (weakest) to L5 (strongest). Symptoms vary from mild paranoia to full-blown psychosis, depending on the severity.