“

My duty to keep watch over you is over. No... I want it to be over. —Gaignun to Rubedo, upon sacrificing himself.

”

Gaignun Kukai, true name Nigredo is the chairman of the Kukai Foundation under the alias of Gaignun Kukai, a special organization based in Miltia, Nigredo is a genetically altered clone of professor Dmitri Yuriev, along with Rubedo and Albedo, but they consider themselves brothers. However, due to the fact that cloning is now considered taboo, Jr. charades as Gaignun's legally adopted son. He is the perfect leader for the massive and wealthy Kukai Foundation. Gaignun has black hair and deep green eyes. He has a gentle personality and is well respected both within and outside the Foundation. Gaignun is listed as the first son and heir to the industrialist Soze Kukai.

Gaignun Kukai is really U.R.T.V. Unit #669, who is a biological weapon des

igned to combat U-DO. U.R.T.V. Unit #669 is nicknamed Nigredo, a reference to his black hair. Gaignun can telepathically communicate with Jr. and Albedo and can use his voice to hypnotically manipulate people, if need be he can telekinetically destroy a person. "Kukai" was a fictional persona created by the Second Miltian government as a means to pool their special operation funds. Following the Miltian Conflict and Helmer's rescue of Gaignun and Jr., they took on the Kukai surname to justify and establish the Kukai Foundation. This also allowed the U.R.T.V. units to live their lives more normally.

In Episode II, Gaignun's past relationships with Albedo and Jr. are explored. which include subconcious dives into Sakura Mizarhi's mind in order to allow her to speak once again. These adventures showed the rift growing between the trio of U.R.T.V. units, which eventually led to a breakdown during the Miltian Conflict, causing Albedo to come into contact with U-DO and become insane. At the end of Episode II, Gaignun apprarently suffers from a double personality; one part is Gaignun, the other is Dmitri Yuriev. Dmitri most likely created Gaignun just as a host for his body, for Dmitri has transmigrated from body to body for over 100 years (according to Pied Piper).

Gaignun shares his name with the horse Roland, a general of medieval French King Charlemange and wielder of the legendary blade Durandal rode into battle on. Kukai is also the name of a famous Japanese Buddhist monk; Buddhist undertones can also be seen in Xenosaga. The name Nigredo refers to the philosophic beliefs of Carl 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.

In the series, Jr. and Gaignun both raised a cat named Gaignun, which is the origin of Nigredo's alias.