Haku (yōkai)

was a yōkai that devoured humans for their life force. It was killed by Hakudōshi when he and Kohaku were pursuing it. Hakudōshi had bisected it and had Kohaku open it's stomach in order to claim the human life force it had absorbed from its human victims. This was done to create a puppet that would protect Naraku's heart. His puppets would soon lead to the creation of Mōryōmaru that had a human form because the haku that was used to form him was from humans.

Manga vs. Anime

 * In the manga, a scene was shown of Haku eating many human soldiers before being killed by Hakudōshi. This is not seen in the anime.

Haku (Yōkai) 魄妖