"Noah's Secret", known as "A Deepening Mystery - Noa's True Identity" in the Japanese version, is the one hundred and tenth episode of the Yu-Gi-Oh! anime. It first aired in Japan on June 11, 2002 and in the United States on January 10, 2004.
Noah brainwashes Mokuba by using a projection of Kaiba to verbally abuse him. In the original Japanese version, the projection strikes Mokuba across the face before storming away. Mokuba is brainwashed by Noah and starts to believe Noah is the only one he can trust.
A tunnel created by Noah leads Kaiba to Mokuba, who refuses to go with him, in favor of staying with Noah. Yugi and Téa arrive at a virtual copy of the dilapidated Kaiba manor. Following the cries of a baby, they find within the manor a framed portait of Noah posing with Gozaburo. Another door takes them to Noah and Kaiba as Noah shows Kaiba a projection revealing that Noah is Gozaburo's son, and he originally planned to adopt Kaiba in order to motivate Noah in his studies. Yugi gives Kaiba the portrait of Noah and Gozaburo, who disregards the entire story as false because the photo was dated six years previously, but Noah has not aged since then.
Meanwhile, Crump, Johnson, Leichter, and Gansley chase the rest of the gang in an attempt to forcefully steal their bodies. Joey summons five monsters to stall them and they attempt to escape in the truck.
After a harrowing chase, Noah rescues the gang from The Big Five since stealing their bodies by force is against his rules. Everyone except Mokuba is reunited shortly afterwards.
Back in the real world, Yami Marik is growing tired of waiting for Yugi and the others and decides to try to find out what happened to them.
Differences in adaptations
- In the original, Marik knows about what Noah is doing to the gang, while in the dub he knows nothing about what is happening in the virtual world.
- In the Japanese version, when Mokuba runs toward Noah's projection of Seto, Seto slaps Mokuba across the face, leaving a red mark and causing Mokuba to fall to the ground. This scene is removed from the dub, and only the scenes of Seto raising his hand and of Mokuba on the ground are shown. The red mark on Mokuba's face is also removed.
- Cut from the dub is a shot of the truck that the gang is in swerving while The Big Five chases them.
- In the Japanese version is a shot of Leichter/Jinzo hitting the truck, causing the truck to topple over and Otogi (Duke) to fly off. In the dub, this scene is not shown but is implied through sound (Duke's yells) and the scenes that precede and follow it.
The following cards appeared in this episode. Cards in italics debuted here.