An accident during tests of an anti-plasma artificial magnetic shield at Japan's Ground Self Defense Force East Fuji practice range sends the 3rd Special Experimental Company, under Colonel Matoba on a time-slip 460 years into the past, into 'the Age of civil War'. At the same time an imaginary-number anomaly thought to be caused by interference from the past begins eroding the present, opening up widening time-space 'holes' all over Japan.