D/D/D/D

DDDD ( DīDīDīDī) is a sub-Archetype of the "" Archetype, and is thus an even further sub-Archetype of the "DD" Archetype. They are stated to be 's true power.

According to Taylor Gorrell, "DDDD" is short for "Different Dimension Demon Dragon" (ディファレント・ディメンション・デーモン・ドラゴン Difarento Dimenshon Dēmon Doragon), and as such, all "DDDD" monsters have primarily dragonic forms and are treated as Dragon-Type monsters in addition to their printed Fiend-Type.

Design
All "DDDD" monsters are evolutions of the "DDD" monster respective to their secondary Type, sharing their Attribute and being Summoned by the evolution of whatever Summon their original form was Summoned by, usually requiring their original form as a Material. Their actual names are two words, the first word being a synonym for the Underworld or Hell from a different mythology, and the second word being a word related to their element or otherwise.