Sin Sin is a major antagonist in " Final Fantasy X " . It is a gargantuan whale - like beast which threatens the world of Spira . It was named by the people of Spira who believed the beast came into being as punishment for their ancestors relying on machina and becoming a hedonistic society . By following the teachings of Yevon , the people of Spira believe one day they will atone for their crimes and Sin will vanish . Sin is represented by the letter Z in the Yevon script alphabet . It appears in many places in " Final Fantasy X " , sometimes paired with the letter A , the symbol of Yu Yevon , symbolizing the beginning and the end of things . Profile . Appearance . Sin has a whale - like body that it moves with a pair of clawed arms , as well as hind legs resembling pectoral fins for movement in water . It has a long tail and its body is encased in scales it can shed and turn into small monsters known as Sinscale s . It carries part of a city presumed to be a part of Zanarkand on its body close to the back of the head . Sin ' s final form has feathery wing - like protrusions that are purple at the tips . Abilities . According to " Final Fantasy X Scenario Ultimania " Sin ' s body is composed of pyreflies and in that respect , it is no different from a common fiend . However , Sin draws in pyreflies to replenish its strength whenever damaged , and thus conventional attacks cannot defeat it . According to the " Final Fantasy X Ultimania Omega " , its body is formed as a result of gravity magic used to draw in further pyreflies from the atmosphere , and compressing them densely . Sin can recover the separated parts of its own body , known as " Sinspawn , " because Sin can repair its body more efficiently by taking in pyreflies that have already been condensed , rather than freshly absorbing pyreflies that drift around the surrounding areas . Sin ' s destructive capabilities are tremendous , as it can control gravitational forces and thus fly . People who touch Sin are sometimes carried , unharmed , to remote places . This is because Sin ' s body is supple and can suck up those who touched it and then expel them . People who have gotten close to Sin may get muddled up and experience hallucinations . This is called " being affected by Sin ' s toxin , " but the true reason is that the high density of pyreflies that form Sin ' s body have an adverse affect on the low - density amounts of pyreflies present within the bodies of those who approach it . Sin is immune to most conventional forms of weaponry and is highly resistant to attack , able to project a barrier to protect itself . Spirans believe that only the Final Aeon can kill Sin , and all attacks the party wages on Sin in " Final Fantasy X " only serve to wound it . Sin ' s signature attack is a huge blast of energy from its mouth known as " Giga - Graviton , " an attack so powerful it can induce tectonic plate movements visible from outer space . Its other body parts are capable of using lesser Gravity - based attacks . Sin has an affinity for water , and can often be encountered lurking in such an environment . It can blend into , absorb and use the water it inhabits as a weapon . Whether Sin ' s abilities change depending on which Final Aeon forms its core is unknown . It is implied the post - Braska ' s - Calm Sin never reached its full strength , as the Final Aeon at its core still exerted some influence over it , slowly being taken over by Yu Yevon . Story . " Final Fantasy X " . Sin was created during the Machina War between Bevelle and Zanarkand a thousand years ago . Bevelle relied on machina for weapons and Zanarkand used summoners . When Zanarkand was losing , Yu Yevon , a summoner of Zanarkand and its leader , devised a plan to both defeat Bevelle and preserve the city of Zanarkand forever . Yu Yevon called the surviving people of the city together and transformed them into fayth as conduits for a massive summoning that created a spectral version of Zanarkand from the dreams of the former Zanarkand inhabitants . Yu Yevon set this dream Zanarkand out to sea , then called pyreflies to himself to craft the first Sin . This was the only Sin that never had an aeon at its core . Sin was given the objectives of protecting the summoning of dream Zanarkand , ensure it was not discovered , and to destroy any city that grew too large or relied too heavily on technology . The strain of trying to control Sin was beyond Yu Yevon , and the process destroyed his mind , removing any conscious control he may have had on it . Sin thus became a monster guided by its instincts , and indiscriminately attacked the machina civilizations all over Spira , starting with the true Zanarkand itself . Yu Yevon was reduced to a husk that existed only to summon . To allow Spira a reprieve and hope for salvation , Yu Yevon ' s daughter , Yunalesca , presented a way to destroy Sin : the Final Aeon , a powerful aeon born from a bond of love . Sacrificing her husband Zaon for the ritual , he became the Final Aeon and destroyed Sin , but the Final Summoning killed Yunalesca . Yu Yevon ' s spirit possessed Zaon ' s body , and over time transformed a new Sin with Zaon ' s Final Aeon at its core . During this time the new Sin was too weak to terrorize Spira , establishing a temporary time of Calm . Apparently the only one able to create the Final Aeon , Yunalesca became an unsent and remained in the Zanarkand Dome to create a new Final Aeon for summoners who complete their pilgrimage . As told in the official timeline in " Final Fantasy X Ultimania Omega " , during the First Calm the survivors began reconstructing Spira , focusing on Bevelle . After Yu Yevon had regenerated Sin Spira ' s plight began anew . The second incarnation of Sin destroyed the remaining machina civilizations and thus machina use began to fall out of favor . The Yevon temple was established in Bevelle and the teachings of paying homage to Yevon and Yunalesca , and preaching of machina prohibition , were adopted by the world at large . Seizing public sentiment , the temples took control of Spira . The new religion established Sin as a punishment for people ' s sins spreading the story that the Calm will arrive with the Final Summoning . The temples shifted the blame of Sin ' s return onto the people of Spira , and brought about stability by leaving them with the hope that once they atone Sin will go away . In truth , Yunalesca and the upper echelons of the Yevon temples know Sin will always return , but their teachings give Spira hope and keep its citizens from giving in to despair . Some six hundred years later a summoner named Gandof defeated Sin , tearing the Calm Lands asunder and isolating the Remiem Temple , thus creating the Second Calm and becoming the first high summoner . Gandof suffered the same fate as Yunalesca had and died . This gave credence to Yevon ' s teachings , and doubts about the temples subsided . As before , the Calm was short - lived , and Yu Yevon rebuilt Sin which started its rampage as the third Sin appeared with Gandof ' s Final Aeon as its core . Gandof was posthumously titled " high summoner , " a title which would from then on be bestowed on all who defeated Sin . Statues of him were placed in Yevon ' s temples and his story was told to all Spirans as an example of honor and sacrifice to be followed . To defeat Sin , summoners would journey through a series of temples , gathering powerful aeons at each one in preparation for obtaining the Final Aeon in Zanarkand and combating Sin . For a hundreds of years this cycle continued — summoners would go on a pilgrimage to hone their abilities as they traveled to the ruins of Zanarkand and met Yunalesca , who would transform one of their guardians into a new Final Aeon . The summoner would give his or her life to destroy Sin with the Final Summoning , and Yu Yevon ' s spirit would possess the Final Aeon and turn it into a new Sin . As Sin attacks large settlements , Spiran towns rarely grow beyond a certain size . The biggest city in Spira is Bevelle , followed by Luca , but countermeasures are taken so that those cities aren ' t attacked by Sin by having the Crusaders attract Sin ' s attention and avert its course . Braska , Jecht and Auron are the most recent band of summoner and guardians to defeat Sin . They made their way to Yunalesca and Braska obtained the Final Aeon . Though Braska held onto the hope that this time Sin would not return , Auron believed otherwise . Jecht , originally a citizen of dream Zanarkand who had accidentally ended up in Spira , became Braska ' s Final Aeon . Before this he tasked Auron with finding a way to the dream Zanarkand and taking care of his son , Tidus . The Final Summoning killed Braska and Jecht became the new Sin . Ten years later , Jecht , still aware within Sin although only barely , brings Sin to dream Zanarkand , and he and Auron take Tidus into the world of Spira . As Tidus travels with Braska ' s daughter Yuna as her guardian , Auron accompanies them and teaches Tidus about Jecht and Braska . Tidus is made aware of Jecht ' s spirit resting within Sin , and is told Jecht wants Tidus to kill him to free him from his fate of terrorizing the world . They run into Sin many times and witness the destruction it brings forth . When the party confronts Yunalesca she tells them the Final Aeon would not destroy Sin permanently , but Braska chose this path to give the people of Spira hope . Yuna disagrees , saying her father believed he could free Spira . Denouncing the tradition as false hope , Yuna refuses to sacrifice one of her guardians . Yuna and her guardians destroy Yunalesca , and with her the way to create a new Final Aeon . Now made aware of Yu Yevon ' s existence , Tidus suggests a new way to destroy Yu Yevon ' s spirit within Sin . The party wages a full scale attack on Sin with the airship , " Fahrenheit " , and enters its mouth . In the deepest part of Sin they find a recreation of the dream Zanarkand in ruins , where Jecht awaits them . The party destroys Jecht in his Final Aeon form and Yu Yevon emerges . Yuna calls her aeons one by one and Yu Yevon possesses them , and the party destroys them as well . With no aeons left to control Yu Yevon becomes vulnerable and is killed . Yuna performs a sending to place his spirit at rest . With Yu Yevon ' s defeat , Sin explodes , and the Eternal Calm begins . " Final Fantasy X - Will - " . The Farplane has become unstable to the point that beckoning outside of it manifests the dead in Spira . Sin returns , ending the Eternal Calm , and Yuna theorizes it was the result of someone beckoning it . She delivers a speech to a crowd of people announcing she will defeat it once more . Gameplay . Inside Sin . The inside of Sin , aptly known as Inside Sin , is the game ' s final dungeon . The party enters inside the beast after having penetrated its armor , and make their way to the center where they face Braska ' s Final Aeon , and eventually , Yu Yevon . The fiends within Sin are powerful , but if the player defeats them they gain valuable AP . Sinspawn . Sin can create smaller creatures , Sinspawn , from its outer layer . Coming in a variety of shapes and levels of power , the Sinspawn cause trouble for any person that crosses them until Sin arrives and reabsorbs them . Boss . Sin ' s various body parts are faced several times during the game . Creation and development . Sin was created to be a presence Spirans could not avoid however much they tried . Director Yoshinori Kitase created it to represent the kinds of calamitous disasters that exist in the real world , such as earthquakes and typhoons . Spira has the teachings of Yevon , which give meaning to people ' s lives in the face of death , so what Kitase really tried to show in " Final Fantasy X " , was how people behave in the face of unavoidable fate . Having ruins become a part of Sin ' s physical form helped to visually cement the idea it is an " unimaginably ancient monster on an unprecedented scale . " Sin ' s broad physical shape is modeled after a whale to give the impression of the being ' s size , as well as its intelligence and otherworldliness . The plot of " Final Fantasy X " alludes to the famous Japanese story of and the . Susanoo ( Tidus ) is banished from his home in the Heavens ( Dream Zanarkand ) and trying to win back favor to return home . He comes to the mortal world ( Spira ) and comes across two earthly deities who are weeping because they have to sacrifice their daughters ( summoners ) to the evil Yamato - no - Orochi ( Sin ) to keep it from destroying their home . They wish to save their eighth daughter ( Yuna ) from being devoured , so Susanoo comes up with a plan that involves getting the dragon - snake drunk with wine ( " Hymn of the Fayth " ) and killing it in its drunken state . " Yamata - no - Orochi " literally means " 8 - branched giant snake " and is often translated as the Eight - Forked Serpent in English , is a legendary 8 - headed and 8 - tailed Japanese dragon . Early concept artwork for " Final Fantasy X " show serpentine or octopus - like Sin prototypes with multiple appendages . When asked why Sin was brought back in " Final Fantasy X - Will - " , Kitase commented that similar to how Sephiroth ' s role in " Final Fantasy VII " , Sin plays an important role in " Final Fantasy X " and the developers wanted to keep Sin involved with the story . " We can ' t say what happens to Sin after the radio drama , we wanted to leave something up to the player ' s imagination . " Other appearances . " Final Fantasy Airborne Brigade " . Around January - February 2013 , Sin was one of the opponents available . " Final Fantasy Trading Card Game " . Sin appears and is represented by Dark - elemental cards . He is depicted in a screenshot from a " Final Fantasy X " FMV and a Yoshitaka Amano artwork .