One thousand years before the events of Final Fantasy X, Zanarkand was at war with Bevelle, a strong military power which used mechanical technology to build weapons (Zanarkand's machines were used solely to power the city). Unwilling to let Zanarkand die in defeat, Yu Yevon had all the surviving citizens turn themselves into Fayth and began a massive group summoning of the city, one that never slept. In order to protect himself, he gathered a multitude of pyreflies and transformed them into an armor which became the monster, Sin.
Yu Yevon gave this creature a set of very simple instructions: destroy any machina or settlement which grew larger than a small village in order to bring technical evolution to a halt, and retaliate to all hostility with extreme prejudice. However, the strain on summoning both Sin and maintaining his beloved Dream Zanarkand proved too much, even for his abilities. His humanity soon faded and Sin was left as a force relying solely on instinct and to comply with the instructions given to it upon creation. Sin's first act as such was to destroy the real Zanarkand. The armies of Bevelle saw this destruction and retreated, bringing the first news of the great monster. According to the fayth who continuously summon Dream Zanarkand, Yu Yevon is neither good nor evil. His existence only has one purpose; to summon his armor known as Sin, which is why he is drawn to the Final Aeon when his former armor has been destroyed, and to maintain Dream Zanarkand.
Shortly before creating Sin, Yu Yevon informed Yunalesca of his plan and gave her a means of calming the creature. Yunalesca passed this knowledge on to the leaders of Bevelle, thus beginning the teachings of Yevon and the endless spiral of death that surrounds Spira.
Every time a Summoner destroyed Sin, the Aeon used for the Final Summoning would be possessed by Yu Yevon and used to rebuild Sin. Yu Yevon continued to use this process to renew Sin time and time again. However, 1000 years after Sin was born, Yuna and her guardians pierced Sin's armor and defeated Yu Yevon himself, thus banishing Sin for good.
His personality is also utterly unknown as he has no dialogue in his single appearance.
Also, his appearance is somewhat of a mystery, as he is never shown in human form. He appears as a bizarre, floating creature with hooks and a glowing emblem of Yevon for a face. The nature of this form is never explained, but there are many possibilities. It may be that transplanting his soul from each Sin to its successor may have diminished or destroyed his true physical form, leaving him in this parasitic, bug-like state. He also may have taken on this form intentionally, perhaps to facilitate his ability to possess Aeons. Another possibility is this form is actually his appearance as a fiend; this is unlikely, though as he retains his obsessive desire (and the ability) to summon Dream Zanarkand.
He also appears shortly as a floating ball of light similar to a Pyrefly to signify his ethereal form.
Despite being the main antagonist, a character integral to the storyline, he has less detail given about him than many of the side characters. The only information given about him comes from other sources, such as Bahamut's Fayth, Yunalesca, and Grand Maester Mika, making him akin to Sorceress Adel from Final Fantasy VIII. All that can be assumed is that he seemed to care more about Zanarkand's memory than the citizens of Zanarkand themselves.
Yu Yevon's role in the story seems to be that of an impersonal antagonist. While Jecht and Seymour filled the roles of personal antagonists for Tidus and Yuna, Yu Yevon has no personal connection with any of the main characters.
The Yu Pagodas combine together around Yu Yevon, and then they all dissolve in the same way as Chaos after his defeat. This is the first time this style of death is used since Safer∙Sephiroth in Final Fantasy VII.
Yu Yevon is the final boss of Final Fantasy X. He is accompanied by Yu Pagodas.
|Tidus - Auron - Rikku - Wakka - Lulu - Yuna - Kimahri|
|Temporary playable characters|
|Jyscal Guado - Kelk Ronso - Wen Kinoc - Yo Mika|
|Chappu - Clasko - Elma - Gatta - Lucil - Luzzu - Lord Mi'ihen|
|Belgemine - Braska - Dona - Gandof - Isaaru - Ohalland - Yocun - Yunalesca - Zuke|
|Barthello - Biran Ronso - Borra - Brother - Calli - Cid - Ginnem - Jecht - Maechen - Maroda - O'aka XXIII - Omega - Pacce - Rin - Shelinda - Tidus' Mother - Tromell - Wantz - Yenke Ronso - Yu Yevon - Zaon|
|Baaj Temple - Besaid Island - Kilika Island - Luca - Mi'ihen Highroad - Mushroom Rock Road - Djose - Moonflow - Guadosalam - Farplane - Thunder Plains - Macalania - Bikanel Island - Bevelle - Calm Lands - Monster Arena - Cavern of the Stolen Fayth - Remiem Temple - Mount Gagazet - Zanarkand - Zanarkand Dome - Omega Ruins|
|Al Bhed - Guado - Hypello - Ronso|
|Aeon - Blitzball - Butterfly Hunt - Calm - Celestial Weapon - Chamber of the Fayth - Chocobo Knights - Cloister of Trials - Eternal Calm - Fahrenheit - Fayth - Fiend - Final Aeon - Guardian - High Summoner - Hover - Jecht Shot - Machina - Maester - Overdrive - Overdrive Mode - Overkill - Pilgrimage - Pyrefly - Rin's Travel Agency - S.S. Liki - S.S. Winno - Sending - Shoopuf - Sin - Sphere - Sphere Grid - Summoner - Unsent - Warrior Monks - Yevon|
|Original Soundtrack - Promo CD - Suteki da ne - Vocal Collection - Feel/Go Dream: Yuna & Tidus - Piano Collections - Official Soundtrack
|Abilities - Armor - Auto Abilities - Black Magic - Characters - Chronology - Enemies - Enemy Abilities - Items - Locations - Ronso Rage - Translations - Walkthrough - Wallpapers - Weapons - White Magic|