Dimensional counterparts

"The phrase recited before the Japanese opening themes for the Yu-Gi-Oh! ARC-V anime, during the Heartland City arc."

- The world is divided into four dimensions. In them there are four boys with the same face. The dragons they have call for each other. As if seeking out each other...

A dimensional counterpart is a phenomenon featured in the Yu-Gi-Oh! ARC-V anime, in which a person from one of the Four Dimensions resembles another person from another dimension. In addition to sharing the same face, the counterparts seem to be drawn to each other for an unknown reason. Yuya Sakaki and Zuzu Boyle are the only characters to have dimensional counterparts.

History
Accordingly to Leo Akaba's actions, it is stated that these counterparts are important to his plans. He is interested in Celina's unknown abilities and also expresses interest in getting a hold of Zuzu Boyle, stating that she is the "fourth piece" he needs, having already had Yuri capture Lulu and Rin for him.

Mistaken Identities
A common recurrence is for a character to confuse one counterpart with another counterpart due to their identical facial structures. Instances of confusion include:

Yuya Sakaki
Yuya was the first character to have a dimensional counterpart. These counterparts each have a Dimension Dragon, can enter a rampant state of mind, and sync with each other. If a counterpart has absorbed another into his body, the one absorbed can possess the other's body. Each of Yuya's counterparts serve as the secondary protagonists of the series, except for Yuri who currently serves as a major antagonist.

Zuzu Boyle
The second character to be known to have dimensional counterparts was Zuzu. Similar to how Yuya and his counterparts each possess a Dimension Dragon to help signify themselves as counterparts, Zuzu and her counterparts each wear a bracelet, which have mysterious abilities. For this very reason, they are collectively called Bracelet Girls (ブレスレットの, Buresuretto no Ko). Zuzu currently serves as the main secondary protagonist and Celina as one of the main supporting characters, while Lulu and Rin are currently minor characters.