The Charon Virus is an airborne disease that can cause asphyxiation in the immune system. The Charon Virus affects only primates, and is harmless to birds. This virus first developed inside Nageki Fujishiro, and was later transferred to Ryouta Kawara.
The Charon Virus can completely stop a human's immune and respiratory systems within three minutes. It was a key component of Operation Hatoful.