In an alternate world, the Cold War has continued to persist for 140 years. As a result, the world was divided into two factions: the West Block, and the East Block. As the Cold War drags on, the tension between the two factions, as well as the amount of nuclear weapons they have, rise. Mylene Hoffman is a female cyborg who is a spy for the West Block. Together with three other agents, Mylene partakes in various missions issued by her superiors.
After discovering that Neuroi are capable of communication with humans and making peace with the nest above Gallia, the Witches squads are now on a mission to re-establish communication when the Neuroi completely vanish after a sudden attack. It is then that they discover a new massive nest that just appeared covering almost all of Europe. Ruthless and without mercy it annihilates allied forces along with many Witches. Word of the attack reaches Fuso and a support battalion is deployed to rescue the survivors. Among the rescue team is the former Striker captain Sakamoto Mio and the now civilian Miyafuji Yoshika who wants to save her dear friends.