Absolute, rule-bending supernatural manifestations granted by Witch Factors, existing outside the natural framework of world mana and magic.
Q: When ingesting a Witch Factor, what reaction occurs if the host lacks natural compatibility?
### Regarding the contrast between Echidna and Subaru in Arc 4 Echidna's proposed contract was logically the most efficient solution with the minimal statistical casualties. However, it was predicated on completely grinding down Subaru's soul. Subaru refusing her hand was solely because he chose 'foolish stubbornness that refuses to accept anyone's sacrifice' over cold efficiency.
Q: When Echidna offered a contract to Subaru, did she possess any genuine human affection or romantic feelings toward him?
Q: What is the maximum number of 'Unseen Hands' Petelgeuse can manifest simultaneously? How does it differ from what Subaru can use?
Q: Is the phenomenon where memories of victims struck by the White Whale's 'Fog of Elimination' vanish from the world based on the same principle as the Sin Archbishop of Gluttony's Authority?
Q: How are the save points for Subaru's 'Return by Death' determined? Can they be moved by Subaru's own conscious will?
Q: Subaru's magical affinity is Yin attribute, but in world standards, how strong is his gate and mana pool?