|“|| Look! It's got a good luck phrase on it! Sayonara Baby!
- Jr. giving MOMO a bullet braclet
Gaignun Kukai Jr, true name Rubedo, is a director of the Kukai Foundation, an organization based on Second Miltia. He appears to be a child, and is thought by the public to be the son of his fellow director, Gaignun Kukai (thus his alias, Gaignun Kukai Jr.). However, he is actually Gaignun's older brother.
Rubedo was a survivor of the U.R.T.V. (U-DO Retro Virus) unit created by the scientist Dmitri Yuriev to combat U-DO, a mysterious waveform that threatened to destroy the galaxy. Rubedo's unit number as a U.R.T.V. was 666. He possesses the unique abilities of all U.R.T.V.s, including telepathy and various telekinetic powers. However, despite being a "designer child," he was born with his twin brother attached to him through the heart—a problem that was remedied when they were separated. He is the strongest U.R.T.V., vessel to a power none of the others possess—including the other variants—and reputed to have the one perfect anti-U-DO wavelength, and was therefore made their leader. Although to date he hardly uses his unique powers compared to his living brothers instead preferring to fight with his guns or machines, Albedo states that Rubedo is weaker than he was before either indicating a lax in training or that he himself has become much stronger. A bit of both but more the former. Rubedo, while his formerly conjoined twin brother was called Albedo, U.R.T.V. #667. Gaignun Kukai was the last brother, christened Nigredo.
Over the course of the first two games, Rubedo and MOMO, a 100 Series Observational Realian, grow very close to each other, somewhat due to MOMO's resemblance to the model she was built after, Sakura Mizrahi. Before her "death," Rubedo and Sakura shared a juvenile romance.
While Jr. looks like a child, and can act rashly, he is also capable of making tough decisions and cutting observations. He also has a fondness for guns, action movies, and classic novels, including The Adventures of Robinson Crusoe, The Wonderful Wizard of OZ and Twenty Thousand Leagues Under the Sea. Because of his hobbies Jr. is a master of gunplay, especially with pistols and enjoys fighting akimbo. At the beginning of Xenosaga Episode I, Rubedo, using the name Jr., carries a pair of Rook Company pistols. However later, and in Episode II he wields two antique Makarov pistols, they are mistranslated as "Makalov" in the English version likely due to the lack of the "r" in Japanese. The Makarov was originally a soviet built pistol, taken from designs acquired from the Third Reich at the end of World War II. The Makarov is a 9x18mm caliber.
During the Miltian Conflict, Rubedo and the other URTVs fought against U-DO before the planet’s disappearance into the void. As leader of the URTVs, Rubedo was responsible for keeping them connected through a spiritual link, which would protect them from U-DO’s destructive powers. A moment before the U.R.T.V.s were to destroy U-DO, Rubedo had a vision of the Old Miltian planet being destroyed when something monstrous emerged from within. Rubedo, fearing for the lives of his companions, broke the Spiritual Link leaving the other URTVs with no protection against U-DO. U-DO slew or drove mad all of the standard U.R.T.V.s, as well as Albedo during the fighting, Rubedo carried an injured Nigredo several minutes before Canaan and chaos rescued the U.R.T.V. duo on the E.S. Asher. Therefore, the only documented surviving U.R.T.V.s were Nigredo and Rubedo, though Albedo survived as well. In the original version of Soraya Saga's EPISODE II script U.R.T.V. #668 Citrine survived the Miltian Conflict as well, but she was edited out of the final version of the game.
He is one of the "variants," U.R.T.V.'s who undergo a stimulated mutation along with Albedo, Nigredo, and Citrine. Superficially this caused his hair to turn a bright red and his eyes a deeper blue but more significantly it allowed him to pause his cellular development. This allowed him to retain his youth, however in Xenosaga: The Animation, it is suggested that this somehow staved off infection from U-DO or halted some form of physical trauma. The original version of Soraya Saga's Episode II script called for Jr. to suddenly unpause his development and rapidly mature into an adult version of himself. For some reason this idea was thrown out by Monolith Soft's new team of writers and editors. While this did not appear in Episode III, a brief glimpse of Jr.'s "true form" was shown to him by Gaignun. In addition to that he has some unique power called "Red Dragon Mode", not much is known about this save that it briefly created a dragon-like shadow and manifests as a blazing red aura and only manifests in periods of extreme stress. This apparently boosted his power though we are shown no significant effects other than it was used to kill Albedo. Part of Gaignun's role as a U.R.T.V., besides being the future host of Dimitri Yuriev's consciousness seems to be a living stop-gap meant to keep Rubedo's "Red Dragon" from going out of control.
Because Rubedo and Albedo began life as conjoined twins, the two share similar but opposite powers regarding the regulation of their cellular growth. Rubedo is able to slow down his aging at the cellular level, thus his youthful appearance, while Albedo is able to speed up cell growth to the point of being able to instantly regenerate any part of his body. Neither appears to be capable of dying of natural causes because Rubedo never ages past a juvenile state and Albedo's cells constantly regenerate themselves.
The name "Rubedo" refers to the philosophic beliefs of Karl Jung, who believed that the process of self-realization has three major steps, which he named using terms derived from alchemy, which he studied prior to developing his theories. These three steps are known as Negredo, the death of the old, perceived self, Albedo, the discovering of one’s inner identity, and Rubedo, the process of living a self-aware life.
666 is the number of the Beast (also called the Anti-Christ), a seven-headed emissary of the Devil in the Book of Revelation and alongside his power of the Red Dragon Jr. is set up as a demonic character superficially but lacks any such personality traits. However, the comparison to the anti-christ is fitting considering he was designed to produce the anti-wave of U-DO, a god.
- As stated by the developers, Jr. was supposed to be physically mature in Episode II before the final version of the script was produced.