Q (S from Romania): According to True Assassin, Servants cannot fight back against the
shadow and the pure Saber will lose her sanity by merely touching it. Does this “purity” refer
to how Saber is a hero and not an anti-hero?
N: Correct. A straightforward Heroic Spirit has immunity against curses, so their Spirit Origin will be
corrupted along with extreme pain. For an anti-hero, who is “closer to source”, there will be some
corruptiuon but no extreme pain, giving them a slight mental advantage for them to think, “Oh, this
isn’t good, this really sucks”
T: So, to the certain darkest of darkness, it would be like soaking in the hot springs?
N: Right. But his anti-magical energy and stuff are at the lowest rank, so it’s like “it doesn’t hurt but
will get swallowed up instantly.” Though in his case, he would still take joy in things even after
getting swallowed saying stuff like “By the way, is there a manga cafe around here?”
T: I sense a spin-off in the works! Lethargic cynical everyday life manga, The darkest dark’s Holy
Grail Living in the Cheap Lifestyle!

Heaven's Feel I Booklet Nasu & Takeuchi Q&A