In Japan, there exists a government agency known as the Supernatural Disaster Countermeasures Division (SDCD), whose duty is to protect the citizens from creatures unseen. They are able to dispatch these monsters swiftly and without alerting the general public. But currently, they face a different challenge: the betrayal of one of their own.

Ninomiya is an ordinary high school student who lives at home with his older sister Ryoko. However, Ninomiya's life ceases to be normal the moment a cute girl named Mayu descends into the middle of his school's campus in a military-grade helicopter. It turns out Ryoko sent this girl, along with her older brother Mikihiro, to live at the Ninomiya household.

The story is set in an alternate world called Geminar, where countries have fought endless wars with replicas of humanoid Seikishi weapons that they found in ancient ruins. 15-year-old Kenshi Masaki, the half-brother of Tenchi Muyo! protagonist Tenchi Masaki, is summoned from another world to Geminar.

Viper's Creed is a Mecha action anime series created by Sony Pictures Entertainment Japan with animation by AIC Spirits and Digital Frontier. Though Hiroyuki Kanbe is the main director of the show, Shinji Aramaki is solely responsible for the creation and conception of the show.