Her super isn't an IK nor an astral finish. It doesn't need an install to be used and doesn't kill the opponent from any health range like a proper IK. It's also not an astral finish, since those can only be used at a specific health threshold on the opponent in the last round of a match. The closest thing to it is Dragon Install: Sakkai which isn't health gated like astrals, and only "instant kills" when the opponent is below a certain health threshold.