InuYasha: The Movie 3: Swords of an Honorable Ruler

Untold years ago, the Great Dog Demon wielded the Three Swords of the Fang. When he died, he willed a sword to each of his sons, Inuyasha and Sesshomaru, leaving the third sword, the hate-filled Sounga, locked away forever. But now, the Sounga's power has been reawakened, and the two bickering brothers must put away their sibling rivalry and face off against a force that could spell doom for all mankind.