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. Declan also believes that Yuya and counterparts are also involved in Leo's Arc Area Project due to Yuri and Celina being involved in Revival Zero.

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.

When all four of them are Awakened and their Dragons are Summoned, they chant in unison about merging into a single being. They also have a connection to Zarc.

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). They are also shown to each have feminine decks as nearly all their monsters are female. They were all controlled by the Doktor's Parasite Monsters, making them antagonists, until the Doktor was carded, freeing them. Their decks also possess a synergy to Fusion Summon. They were also split from Ray.