Gaki

Gaki, also called nin-chu-ju-gaki were rumored to be the reincarnated spirits of wicked people.

Description
Gaki were horrible humanoid monsters with several different forms.

These gaunt creatures used their sharp fangs and claws to feast on blood. They could only be harmed by spells or magical weapons. They were able to regenerate rapidly. Fire and cold-based attacks had no effect upon them.
 * Jiki-ketsu-gaki :

This was the most common gaki. They looked exactly like jiki-ketsu-gaki. Instead of drinking blood these gaki ate raw flesh. They could regenerate their tissue damage like all gaki.
 * Jiki-niku-gaki :

These vile gaki carried deadly diseases within their flesh, making them especially dangerous to fight. Wounds caused by a shikki-gaki often killed unless treated by magical means. They were immune to all disease and poisons. Their regenerating flesh could only be harmed by spells and magical weapons.
 * Shikki-gaki :

This form of gaki appeared as a flaming humanoid. They enjoyed smothering their victims with burning fire. Magical weapons were needed to harm them. They regenerated damage but were susceptible to water-based attacks.
 * Shinen-gaki :

Combat
The constant pain wracking their bodies and their uncontrollable needs made all gaki dangerous opponents to face in combat.