It is introduced in the second season as a part of the universe inhabited by the "Neo-Spacians" and "Elemental HERO Neos" the latter of whom is the protector of this world, part of which orbits around Jupiter.
Jaden Yuki was transported to Dolphina, a planet inhabited by dolphin-like creatures, such as "Aqua Dolphin". There "Aqua Dolphin" (now dubbed Aquos) make him familiar with the battle between the light and the darkness, good and evil, and the upcoming threat, the Light of Destruction. Aquos also explained him that he is destined to fight the Light, as he wields the power of Darkness of Justice. At that time, Neo Space was invaded by a Dueling machine, an emissary of the Light. Jaden found Duel Monsters cards in a crushed KaibaCorp satellite, which he designed as a child, including "Neos", "Neo-Spacians" and the "Chrysalis" monsters. Using those cards as his new Deck, he successfully defeated the emissary, but his fight against the Light has just begun. Upon his victory, he was brought back to Earth. As he was fighting the Light, the "Neo-Spacians" would join him in that fight as Duel Monsters cards. They also stood by his side in his fight against the Light-affected Yubel and in the final Duel with Nightshroud.
- ↑ Yu-Gi-Oh! GX episode 62: "A Greater Porpoise"
- ↑ Yu-Gi-Oh! GX episode 154: "Return of the Supreme King, Part 2"
- ↑ Yu-Gi-Oh! GX episode 179: "Farewell, Judai! A Tearful Graduation Ceremony"