The great dog demon who fathered Inuyasha and Sesshomaru left behind three blades: Tessaiga, Tenseiga, and a third, sealed-away sword called Sounga. When Sounga resurfaces in the present and possesses Inuyasha, its destructive will threatens both the modern world and the feudal era, and the spirit of its scabbard, Saya, appears to explain its danger. To contain a weapon that neither can master alone, the half-demon Inuyasha and his estranged brother Sesshomaru are forced to fight side by side. This is the third InuYasha feature film.