D/D

"DD" ( DīDī) is an archetype used by Reiji Akaba in the special Yu-Gi-Oh! ARC-V chapter and anime. So far, they are all DARK Fiend-Type, except for the Extra Deck monsters, which have a different Attribute each.

Design
So far, every "DDD" Monster has been named after a historical military leader, except DDD Hell Armageddon the Great Death Lord which is named after an event.

Etymology
According to Sora Shiun'in, "DD" is short for "Different Dimension". Reiji also revealed that "DDD" is short for "Different Dimension Demon".

Playing style
It revolves around utilizing efficient searching and swarming effects to Summon Fusion, Synchro, Xyz and Pendulum Monsters, as well as manipulating "Covenant" Continuous Spell and Trap Cards to reap their benefits and evade their drawbacks.