4667, 100 years prior to the events of Xenosaga Episode I, Jan Sauer was a Captain in the 1875th Special Operations detachment of the Federation Police Bureau.
During their investigations, he met the widow Sharon Rozas, with whom he fell in love and later married, and her son Joaquin, and learned that Yuriev was providing funding for Voyager's murders.
In Episode II, Ziggy continues to protect M.O.M.O., even beyond his assigned mission, and bonds with Juli Mizrahi after revealing to her that he committed suicide because of Joaquin's death, as the loss of their children caused painful memories for them.
After Joachim's death, MOMO was rescued from her birthplace during the Miltian Conflict and sent to live with Juli on the planet Fifth Jerusalem, the hub of the Galaxy Federation.
6,000 years ago, when he was known as Yeshua, he was one of the disciples of a man whom Ormus would come to worship as their Lord and Messiah and helped to teach humanity and perform miracles in his place.
According to Wilheim and the database, chaos died physically during this time, leaving behind the "Word of Yeshua", also known as Lemegeton, with the Song of Nephilim being an incomplete translation of it.
Although humans are unable to speak these "words", ancient people and future researchers, such as Grimoire Verum, created programs from Lemegeton to control the Zohar.
It also gave him the ability to pause his cellular development and the power of the "Red Dragon" mode, which allows him to amplify the anti-U-DO waves emitted by himself and Standard U.R.T.V.
He also has a fondness for guns, action movies, and classic novels, such as The Adventures of Robinson Crusoe, The Wonderful Wizard of Oz, and Twenty Thousand Leagues Under the Seas.
In Episode III, Jr. comes to terms with issues surrounding the remains of his "family"; his brothers Albedo and Gaignun, his sister Citrine and his father Yuriev.
After joining chaos and Canaan in their search for the U.R.T.V.s, Margulis challenged Jin to a duel which ended in him receiving a gash over his right eye that left a permanent scar.
After learning of Margulis' treachery during the Miltian Conflict, Jin received information from his father Suou and secret intelligence activities under General Helmer, who was then a lieutenant, and became acquainted with chaos.
During the Miltian Conflict, Lieutenant General Helmer sent him and chaos on a mission to retrieve the U.R.T.V.s and the Y-Data, during which the U-TIC Organization activated the Song of Nephilim, which nearly affected Canaan and caused Federation Soldiers in A.M.W.S.
After he and Margulis fought, he entrusted Canaan with information regarding the Miltian Conflict, which is also a fragment of the Y-Data, but something happened that made this data inaccessible to him.
Miyuki Itsumi (ミユキ・イツミ) is a mechanic and systems programmer in Vector Industries First R&D Division involved in the KOS-MOS project under Chief Engineer Shion Uzuki, who created the M.W.S.
When Shion leaves her job at Vector after the events of Xenosaga: A Missing Year, Miyuki keeps in touch with her and offers to help her when she begins to work with the anti-Vector organization Scientia.
Allen is an assistant to Shion Uzuki and the former vice chief of Vector Industries' First R&D Division's KOS-MOS Project Joint Operation Systems Development, who is implied to come from a wealthy family.
In Episode III, Allen is a playable character after Shion is captured by Margulis and the U-TIC Organization on the Past Miltia, and wields a futuristic crossbow.
Tony's piloting skills come into play several times throughout the series; he outruns a squad of U-TIC Auto-Techs by riding the column wall in Hyperspace, gets Shion and her companions into and out of Proto Merkabah and guides the Elsa through a maze of Ormus Society warships.
Haksheen White (ハカセ, Hakase), also known as The Professor, is an eccentric old scientist who designed and built the Elsa Evolution and is obsessed with creating an "Indestructible Giant Robot."
In Episode I, he lives on the Kukai Foundation and, with help from the party, creates Erde Kaiser, a giant combiner-robot made from old parts found in Segment Addresses.
Febronia (フェブロニア, Feburonia), was a Realian belonging to the Uzuki family who ran a small church near the U-TIC HQ on Old Miltia and was Shion's caretaker.
Unit #669, a biological weapon designed to combat U-DO and nicknamed Nigredo (ニグレド, Niguredo) due to his black hair, with Kukai being a persona created by the Second Miltian government to pool their special operation funds.
Yuriev awakened in Gaignun's body during the events of Episode II and reveals his presence to Pellegri on a video link, instructing her with telling her superiors that he has returned.
She was once part of a group of people illegally "owned" by a pharmaceutical company that used them as guinea pigs until Gaignun saved her and Mary twelve years prior to the events of the series and they made the Foundation their new home.
Outside of the Miltian Conflict, he helps in various political matters and handling the "framing incident", as well as arranging to save Shion and her allies on numerous occasions.
The Song of Nephilim is the result of amplifying the wavelength created by the Lemegeton through the use of a giant tuning fork, a system designed and built by Joachim Mizrahi.
[19] KOS-MOS and T-elos have also appeared in the Nintendo DS game Super Robot Taisen OG Saga: Endless Frontier and alongside M. O. M. O. in its sequel Super Robot Taisen OG Saga: Endless Frontier EXCEED, in the Nintendo 3DS game Project X Zone and its sequel Project X Zone 2, and as obtainable Blades in Xenoblade Chronicles 2.
[24] In a review by Edge for Episode III, the site claims that the reason the game scored two 9s by Famitsu, one of which was that "[t]here's a little girl robot [MOMO] whose panties are visible 99% of the time.
[citation needed] GameSpot criticized her beret, which did not appear in the original game, labeling it "jaunty" and deploring its "unfortunate" return in Xenosaga III.