Existing outside the established rules of the Third Period, irregulars were beings brought into existence through illogical or even miraculous ways, such as through virgin conception. Irregulars could bring about a "reformatting" event known as the Re_birthday, and were thus considered the key to bringing about the Four Endings. Out of the pair, one twin usually represented destruction, while the other represented creation; because of this, both were necessary in recreating the world, as one destroyed it and the other created it anew. Irregulars born without their twin counterpart tended to be highly unstable and destructive in nature, to the point of being able to bring about the end of entire worlds. As part of their physicality, they were typically born with blonde hair.
- Unnamed Boy
- Maria Moonlit's children
- Lucif twins
- Ney Marlon
- Allen Avadonia
- Riliane Lucifen d'Autriche
Conceptualization and OriginEdit
- In-universe, the narration calls irregulars the "golden key" to creation; in Deadly Sins of Evil: Master of the Heavenly Yard, Riliane and Allen use a golden key to create the Fourth Period.
- The Twin Blades of Levianta are also said to represent destruction and creation.
- In the Original Sin Story: Complete Edition album booklet, the Ending Boy and Genesis Girl are said to destroy and create the world, respectively.