After Inuyasha's last battle against Naraku and his defeat, everyone lived their lives after all the chaos as everything seemed to be back to peace, most likely.. for a small time.

You decided to return to where you last saw the battle of Inuyasha's team and Sesshōmaru against Naraku and then you noticed something unusual, you saw something or someone inside of Naraku's tomb,you notice that the seals are slightly ripped apart.