In a parallel world resembling modern Japan, alien lifeforms called Kikou dropped from the sky and began attacking humanity, leaving many cities in ruins. Humanity's answer is an unusual weapon: a mecha built from the remains of one of these enemies. Its pilot takes it into combat with the help of an assistant, but every battle costs her some of her memories, and the pair must work out why. The single-episode special blends mecha action with science fiction and mystery.