Ga-Rei-Zero

Synopsis (en anglais)

An elite squadron trained to combat supernatural forces is called in to investigate reports of invisible monsters terrorizing Tokyo, but their mission is complicated by the interference of a rogue exorcist. When the mysterious female slaughters the overmatched attack force, her former comrades are ordered to lock down the crime scene—and forever silence their old friend. (Source: Crunchyroll) Note: This series is a prequel to the manga series, Ga-Rei.