From AnimeNFO.com:

Inuyasha, Kagome and the others have cornered their arch-nemesis Naraku. KagomeÂ’s flying purification arrow and InuyashaÂ’s Tessaiga finally take Naraku! Mysteriously, from that night on, the full moon strangely continues for several days.

At that time, the unearthly appeared before Inuyasha and the others, calling herself "Kaguya, the Princess of Heaven"!

What is the true relation of this greatest of enemies, who controls time freely, to Naraku? Right here and now, a new door opens on the magnificent tapestry of the warring country revolving around the Shikon no Tama!