The Fangire Race (ファンガイア族, Fangaia Zoku) are a race of vampire-like monsters. They are stained glass-based vampires who feed off of the Life Energy (ライフエナジー, Raifu Enajī) of humans to survive. By using glass shard-like Life-Sucking Fangs (吸命牙, Kyūmeiga) to drain the Life Energy to maintain their souls, members of the Fangire Race can assume human forms to hide within everyday society to feed in secret, revealing their forms when their skin takes a uniquely variant stained glass pattern.
When a human's Life Energy is stolen by their Fangs, the victim becomes transparent like glass; and in some cases the body will shatter when touched. Each Fangire belongs to a specific class based on the animal form it takes, and each Fangire has a true name. A Fangire can live up to three times longer than a human, barring being killed. Upon a natural death, the monster's physical body shatters like glass and collapses in a heap.