Einhänder takes place in a fictional future during a war between the Earth colony, Sodom and the Moon colony, Selene. The "First Moon War" resulted in the destruction of most of the Earth's surface and the creation of a totalitarian regime on the planet. The game recounts the events of the "Second Moon War" in which the Moon attacks the Earth again for natural resources. Selene's tactics consists of sending one-man fighter spacecraft called "Einhänder" on kamikaze missions to cause as much damage as possible on the planet before being destroyed. The player takes on the role of one of these pilots attacking the Earth capital city. As the player progresses through the game, the Selenean military satellite Hyperion relays command orders and objectives. The on-board central computer "EOS" synthesizes orders. EOS also records and relays the player's flight and battle record data back to Hyperion. After completion of the last objective Hyperion informs the player that the battle pattern of the latest EOS unmanned fighter is complete. The player is given the honor of being the target of the last EOS test as reward for their heroic efforts. Upon the player's death they will advance two classes and be awarded the Sirius decoration. After surviving the intense barrage of artillery fire of the test, the pilot wonders why they must be terminated by their allies and questions their military leaders' rationale for the war.