Before his revelation, he is known as The Darkness or Black Shadow residing inside Yuuya Sakaki and his dimensional counterparts. He is the incarnation of Yuuya Sakaki (Standard Dimension), Yuuto (Xyz Dimension), Yuugo (Synchro Dimension), and Yuuri (Fusion Dimension). Zarc's growing aggression led him to destroy the Original Dimension and take on a dragon form known as Supreme King Dragon Zarc. During his confrontation with Ray, Zarc's soul was split into four and reincarnated into four different lives. He is the original owner of the Four Dimension Dragons.

(Source: Yu-Gi-Oh! Arc-V Wikia)