Yuuto strongly resembles Yuya Sakaki; people often confuse him with Yuya, and the first time Yuzu Hiragi saw him, she thought he was Yuya in a costume. Yuuto and Yuya have nearly identical faces. Before revealing his identity, his name was displayed as Unknown on-screen and he was called the Dark Duelist in promotional materials and the Dark Masked Duelist by characters in the series.

Spoiler

He is the Xyz Dimensional counterpart of Yuya Sakaki (Standard Dimension), Yuugo (Synchro Dimension), and Yuuri (Fusion Dimension).