Sephiroth appear around 30 years before the start of the game. Professor Hojo and Lucrecia, two employees of Shinra, one of whom participated in the "Jenova Project, a study of the Remains of a being known as Jenova. Wishing to study the effects of Jenova cells of a human subject. Hojo voluntarily Lucrecia and her unborn child to experiment, which is injected with Jenova cells while still in the womb. After his birth, Sephiroth was raised by Shinra, having been informed that "Jenova" was his mother, but without the knowledge of who or what Jenova was. With superhuman capabilities acquired in the Jenova Project experiments Sephiroth showed inhuman strength and speed at an early age, Sephiroth became a member of an elite SOLDIER, with the highlight of his career in Midgar - Wutai war. One year after the war, was aided by his fellow 1 st-class SOLDIERs Zack Fair and Angeal on a mission to deal with rogue traders SOLDIER Genesis, and not rely on Angeal. Soon after completing the mission, he and Zack were sent to investigate a reactor Mako in Nibelheim. It was there that Sephiroth revealed its ugly origins as an experiment and integral role in the Jenova Project and misinterprated this to believe that he is the last Cetra and humans were the cause of their "extinction". This information is corrupted to the point of madness emotionally driven, he begin to burn all of Nibelheim City and go to mako reactor to release Genova
Zack pursued Sephiroth and arrived at the reactor in an attempt to stop him. Although finally releasing Jenova, Sephiroth was caught off guard and stabbed by Cloud, who was armed with Zack Buster's Sword and a thirst for vengeance for what Sephiroth did to his hometown.
In the end, Sephiroth fell off the bridge and into the Lifestream later (while Final Fantasy VII provides that Cloud threw Sephiroth on the edge, Last Order was regarded as Sephiroth jumped off the reactor from the edge of his own volition). Considered dead, Sephiroth traveled the Lifestream, learning the truth of Jenova of nature, before ending up in the north of the cave sealed in Mako while absorbing Jenova's head and the wisdom of the Cetra.
Notions of Sephiroth the apparent death were put to question when Cloud and company were arrive at Shin-Ra's headquarters. A trail of blood was left by a mysterious third party that has devastated the plant. Cloud found murdered on President, impaled by a sword confirmed belonged to Sephiroth. However, "Sephiroth" was really Jenova body assumed by Sephiroth will and remolded his image as the puppet, in order to find and retrieve the "Sephiroth Clones", people who had undergone the same procedure injection Hojo cells as Sephiroth to demonstrate the Jenova Reunion Theory.
Sephiroth's goal, revealed later in the Temple of the Ancients, was on the run from their planet of energy with the help of the Black Materia power, to call Meteor. Aerith Gainsborough, the last Cetra, tried to stop it with her White Materia and its defensive power. Although Aerith succeeded in convening the Holy, Sephiroth appeared and killed before she could fully activate, leaving blank Materia active but unused. Cloud won the Black Materia, but was emotionally manipulated by Sephiroth, then cast Meteor and expected arrival in Northern crater where he was sealed.
At the climax of story, the barrier is penetrated by Shinra's Mako, which allows Cloud and the rest of AVALANCHE descend into North Crater to deal with him. Sephiroth first appeared to as Bizzaro Sephiroth, before he molted leave their cocoon as Safer Sephiroth. With the destruction of their physical body, Sephiroth's spirit made a final assault to mental Cloud in the Lifestream, trying to overcome his will, once again, and claim Cloud body as him. However, Cloud has rediscovered himself and, therefore, his inner strength has grown to the point where Sephiroth no longer had any influence on him. After an intense battle, Cloud finally defeat Sephiroth.Sephiroth is destroyed by Cloud at the end of the game, however, resumed for a short time in the aftermath of Final Fantasy VII: Advent Children, When Kadaj absorb the Genova cell and become Sephiroth avatar even he defeated once again by Cloud. However, he warns that Cloud "Never be a memory," indicating that he will again be challenging Cloud.
Sephiroth Other Appearance in Final fantasy VII Compilation
Final Fantasy VII : Advent Children
In the film Advent Children, which has been two years after the defeat of Sephiroth, and a condition called Geostigma has spread throughout the world, affecting many patients with symptoms of extreme fatigue, open sores on the skin. The lone Cloud is now faced with a strange trio of brothers silver hair, which are the remnants of Sephiroth, the physical manifestations of Sephiroth on the willingness and spiritual energy. His powerful was allowed to bear the Lifestream and leave it before being fully diluted.
The leader is the younger brother Kadaj, which later transformed into Sephiroth after absorbing the contents of a case containing Jenova cells. After his resurrection, Sephiroth reveals that he has been using Geostigma in a scheme to corrupt the Lifestream and give control of the entire planet. He then down in another planet, thus re-enacting Jenova's goal. Sephiroth shows different powers beyond those of the other characters that appear in the film as flight takeoff and cause a huge effort cut section of the tower building Shinra, and even calling the "tainted Lifestream" with a mere wave of his hand to cover the sky. Despite being outmatched finally Cloud defeats Sephiroth with his new Omnislash Limit Break. His last words before the Cloud dissipating, "... never going to be a memory" could be interpreted as meaning that, despite his remains returned to the Lifestream and spirit diluted Sephiroth never really has been and will continue exist in a way or another.
Final Fantasy VII : Last Order
Sephiroth also appear in Final fantasy VII : Last order, an anime movie that tell Cloud past story, this anime also adapted by Square-Enix to create Final fantasy VII prequel which is Crisis Core.
Final Fantasy VII : Crisis Core
In this Final Fantasy Game, for the half of the game, Sephiroth still be a good man, known as legendary hero of SOLDIER and become SOLDIER elite member. But when reached Nibelheim, and find the truth about who excatly he is he start hatred Shin-Ra. And begin to run his evil Plant, however he defeated by Cloud at that time
Final Fantasy VII : Before Crisis
Sephiroth also appear in Final fantasy VII : Before Crisis, in this game he totally be a hero that help the Turks protect Shin-Ra and stop AVALANCHE plan (AVALANCHE at that time full with a bad guy, not like AVALANCHE in Final Fantasy VII that finally be a hero)
Final Fantasy VII : Dirge of Cerberus
Sephiroth appear in a very short scenes in Final Fantasy VII Dirge of Cerberus
Sephiroth also appear in Kingdom heart and Kingdom Heart II with his One Winged Angel and Holding his long sword masamune. Sephiroth appearance also comes in the game Itadaki Street Special, where Sephiroth appears as a playable character along with Cloud, Tifa and Aerith Final Fantasy VII. However, it must be unlocked.
One Winged Angel Theme :