If an undead ningyo attacks in the surprise round, its target must attempt a DC 11 Will save. Success means the target is shaken for 1 round; failure means it is frightened for 1d4 rounds. The target can only be affected by that ningyo's startle once every 24 hours. Creatures with 6 or more Hit Dice are immune to this ability. This is a mind-affecting fear effect. The save DC is Charisma-based.