Satan was the first S-Rank EX-Type Zero in recorded history that was slayed by humans. It appeared in CC 368 and was produced by Queen E-33, the worst calamity so far encountered by humanity.

SS-Class Ingrid technically precedes Satan as the first S-Class EX-Type Zero since it appeared 135 years earlier in CC 233 but Ingrid's designation was posthumously awarded, presumably after Satan.

Satan did not make any appearances in the Knight Run series but it was referenced as a comparison to Cross Eye Alpha and Beta and the intensity of the War of Prayer.


No specifics were mentioned regarding its actions during the Human-Beast conflict but records state that Satan and E-33's Blue Flower ravaged all reachable human worlds in behalf of their Queen. Human defenses crumbled with Satan's attacks and many core planets were subjected to erosion. The war was deemed to be on a scale so devastating that humanity was already at the bring of extinction.

AE and Knights rallied all of their forces together for a desperate final attempt. Their combined efforts somehow defeated Satan and Queen E-33 but it was a pyrrhic victory overall.


The appearance of E-33 and Satan was such a traumatizing event that it provoked significant reforms and innovation since then to prevent another similar disaster from befalling humanity's fate. Due to the high casualties and losses inflicted, the AE was greatly exhausted and could no longer afford to resist any immediate Beast threat. This vulnerability forced the Absolute Defense Line to be scaled down in order to allow humanity's effective fighting forces to still manage a sustainable protection while recuperating. This downsizing meant that certain human worlds had to be left out of the boundary's safe zone or completely abandoned in the wake of the retreat. Humanity also had to painfully learn that even after being destroyed, the shattered debris of Blue Flowers can still cause widespread erosion.

In the wake of this decisive battle, the Knight Order instituted the Cold Hero system to prevent another similar disaster. The Cold Hero system cryonically preserved the Knights who participated with distinction in slaying E-33, Satan, and E-33's Blue Flower, as well as other exceptional Knights thereafter who have proven themselves as heroes.

In CC 422, E-33 and Satan were surpassed as the worst threat to human existence by twin Queens E-99 and E-101 and the Cross Eye Alpha and Beta.

EX-Type Zero Lucifer sought out and absorbed the corpse of Satan after fleeing from its fight with Master Knight Anne Mayer. After gaining Satan's powers, the enhanced Lucifer was then re-evaluated as S-Class.