Inuyasha and Seshsoumaru's father actually had three swords, known and the Swords of World Conquest. Tetsusaiga is the sword of earth and can kill one hundred demons in a single blow, Tensaiga is the sword of heaven and can save one hundred humans in one swing, Sou'unga is the sword of hell and can open the portal and cast the entire world into hell. Inuyasha got Tetsusaiga and Sesshoumaru recieved Tensaiga and Sou'unga was given a seven hundred year seal which wore off in Kagome's time. The sword houses an evil spirit that only a powerful demon can control and it takes over Inuyasha easily. In the end Kagomes somehow manages to get the sword off of his arm by using the "sit" spell and it chooses to use Sesshoumaru's arm and the person who killed Inuyasha's mother the first time to get it's revenge. Can Inuyasha and Sesshoumaru team up for once and defeat this new terror once and for all? Yeah right. -Taken from www.tvtome.com -