Does the technique Kyoka Suigetsu make Rikuo intangible or just create illusions of him?
The ability is named moon mirror because as it was explained "nurarihyon is the reflection of the moon" a distortion, and I would say that it means he can first , slow enemy's perception of him to move faster like an after image technique or second, his body ripples like water to allow him to move around attacks. His only weakness like this is cutting the fear which means his aura is masking himself but those two options are viable. I believe it is a bit of both because he can slow perception to allow him time to move but the ripple allows him invulnerability against weaker attacks because water can only ripple so much.