野岛一成
is an enormous creature that moves through Spira's oceans in its attacks towards mankind, killing a large number of people and destroying towns. It is also capable of flight. Sin's form is vaguely whale-like in appearance, though vastly more massive and the creature is able to release remnants known as Sinspawns. Scenario writer Kazushige Nojima compared with Sin a typhoon due to the disaster it causes in the world.