World of Darkness

The World of Darkness is a realm where humans lose their individuality, and whoever is sent there is erased from the memory of others.

During the fourth season of Yu-Gi-Oh! GX, Trueman and Nightshroud pull several people, including Sartorious, Sarina, Axel Brodie, the many residents of Domino City, all the students at Duel Academy (save Jaden Yuki), and eventaully the whole world, into the World of Darkness.