Stygian Cor

"400 years, it still beats. A thousand nights and days, it still beats. And a million, billion more souls scream and beg, and still, it will continue to beat, even after the sun dims out. Like a mocking, ticking clock that taunts your mortality."

- Azazel giving a speech about the Stygian Cor Stygian Cor (スタイジアン カー, Sutaijian Kaa) are six nigh-indestructible, still beating hearts with a distinct red cross on the organ. All six hearts once belonged to Levya Behma, the Trihexa Dragon, prior to said beast's inexplicable death.

Trivia

 * Stygian is in reference to the River Styx, while "Cor" is latin for "Heart", referencing Levya Behma being essentially the Devil of the Dragon race.