Soul room

A soul room is a room existing within an individual's mind that contains items reflecting their personality.

Shadi was able to access various characters soul rooms through use of the Millennium Key. While inside he was able to redecorate their room to change their personality and have them do his bidding. He was also able to destroy the room in order to kill the person.

By redecorating the soul rooms of Yugi's friends, Shadi forced Dark Yugi into a series of tests.

Character	Information	Image
Curator Kanekura	Kanekura's room was not shown, but Shadi claimed that it stinks of greed and money and is where creatures like Ammit harbor. Shadi released Ammit from that room and had her shatter Kanekura's soul, killing him.
Yugi Mutou	Inside Yugi's mind two soul rooms exist. One for his own soul and one for Dark Yugi's. Yugi's room is filled with games and toys, a display of innocence. Shadi also caught a glimpse of some painful memories of the past, which he would use against Dark Yugi in a later Shadow Game.
Dark Yugi	Dark Yugi's soul room is filled with a labyrinth of staircases and traps. Inside are many other rooms. Only one such room is his true soul room. Shadi tried to take the power of the Millennium Puzzle, while inside here, but was unable to do so until he found the true room. After getting caught in one of the traps, Dark Yugi saved him and advises he leaves. Dark Bakura used his Mind Parasite to implant a portion of his soul into a piece of the Millennium Puzzle to gain access into the soul room. When the time has arrived to find the pharaoh's lost name, Yugi and his friends entered Dark Yugi's soul room to search for it. Inside, they searched many of the rooms, most of which were monsters or traps, as Shadi once experienced. In one particular room, they witnessed the painful memory of the duel between Yugi and Kaiba in Duelist Kingdom, the point which Dark Yugi nearly killed his opponent. Yugi then found out that to locate the real room is for them to desire it. In the NAS anime, Shadi entered Yugi's mind during Duelist Kingdom just to explore. After falling into one of the Traps, Yugi saved him, unsure why Yami Yugi (Dark Yugi) was doing this to him.
Yoshimori	Professor Yoshimori's room consists largely of objects related to his work as an archaeologist. There is one faded picture of his family, indicating he hasn't given them much attention lately.
Anzu Mazaki	Anzu's room contains a picture of the Statue of Liberty and the walls of a ballet studio, reflecting her aspirations to move to America to study dance. There is also a picture of a hero, whose face cannot be seen. This is a representation of Dark Yugi, who has saved her before, but she has never seen him before. Shadi, upon entering this room, noted that Anzu was easy to like.
Mai Kujaku	Mai's soul room is set in a tropical beach with a wooden bridge connecting it to an island. It also contains casino equipment as an objectification of Mai's past as a casino dealer. Dark Marik trapped Mai's mind inside this room as a Penalty Game, inside an hourglass filled with brain-cell eating insects that will destroy her room in 24 hours, thus killing her. She was rescued before that time arrived by Dark Yugi.