Soul Piper

The Tatarimokke (タタリモッケ) or "Soul Piper" in the English dub, is a demon who was born from the souls of dead children. It plays a flute and stays with the child until it is ready to go to either heaven or hell. The eyes are usually closed, but each time a certain soul does wrong (such as Mayu) the Soul Piper's eyes open a bit more. When its eyes have opened completely, the Soul Piper wraps the soul of the child in chains and takes it to the place of its death, where a vortex opens and the soul is pulled by the chains into the depths of hell.

Kagome calls it a poltergeist, or ghost. She goes in it to save a child, Mayu, who thanks her. She almost went to hell herself! Only humans can enter this vortex, thus Inuyasha couldn't go near the portal to hell because he is half demon.