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.



(Source: Yu-Gi-Oh! Wikia, edited)