Holy Mother of Darkness (闇の聖母, Yami no Seibo) and The Knight King's Great Adventure (騎士王の大冒険, Kishi-Ō no Daibōken) are the fifty-sixth episode of the Fire Force anime and the eighth episode of the third season.
As Hibana and the others continue their investigation into the "doppelgangers," Sister Sumire appears before them. From Sumire's words and actions, Hibana is convinced that she is the mastermind behind the "mass spontaneous human combustion incident" that occurred at St. Raffles Monastery. She questions her about the true nature of the "doppelgangers" and "spontaneous human combustion," but...
Summary
Sister Sumire confirms Hibana's suspicions that the sisters were researching doppelgängers, mixing Adolla bugs into the children’s food in the hope of producing Spontaneous Human Combustion (SHC). She is preparing for a second Great Cataclysm and when she reveals that she is the seventh pillar, able to vibrate her body as if shivering and combining with an Adolla burst to produce destructive tremors, Hibana and her friends escape.
Meanwhile as Arthur recovers, Vulcan tells him that the orichalcum in his sword is fake and offers to find him some of the genuine legendary metal which will increase his power. Vulcan plants a series of clues for Arthur to follow, but Arthur misreads the last one and mistakenly deduces that orichalcum is in the Nether.
