A meteorite crashes into Earth, bringing with it a deadly virus known as 'M34' that turns humans into savage beast-like monsters. The world's top organizations gather to form a body known as C.U.R.E. to combat the rampantly infectious disease. One of the organizations, NOA, stands in the virus' destructive path by using soldiers implanted with super nanotechnology. As the virus continues to spread and mutate into ever more deadly strains, mankind's only hope may be a sixteen year-old girl...

Episode 1 - Encounter: The NOA soldiers stand as the best, last and only line of defense against the new virus strains that keep emerging. One soldier, Yuuji, is torn between duty and his place in the world until a chance meeting with a shy girl named Ai, the agency's latest weapon and mankind's newest hope..

Episode 2 - Farewell: Yuuji is hospitalized due to injuries from the last battle as the rest of the NOA team heads off into battle. In the heat of the battle, Ai discovers the horror of the M34 virus as Yuuji confronts her fears and his own insecurities.

Directed by Seiji Muzushima ('Dai Guard', 'Generator Gawl') and produced by Gonzo Digimation ('Full Metal Panic', 'Hellsing'), 'Zaion' has been praised for its plot, character designs and successful integration of CG and traditional cel animation.