Insight doesn't work vs Nastikas

■ Insight is a skill that can be used by the highest-ranked gods who are 4th zen or above, which allows them to see flashes of the other party's current state of mind, their past, or their future. But they can't see any of that with nastikas. Like Agni said in Episode 9, it's something that those who've lived for a long time(?) can do, but it won't work on nastikas who are as old as the gods.

■ However, one way it's still useful is that a sura's non-transformable body parts shine brightly. (Gandharva's blue skin is... not so much a sura part than a color. The part that always stays in sura form is his right eye.) Nastikas are different from other suras, and they almost never completely transform into their sura forms, so normally only a small part of their shadow shines.

S1 E16 Afterword