You may target any player at night, including yourself.
That player must never lie about their alignment the following day in the main game thread, or they will be vanillaised.
An announcement will be made in the morning with who has been targeted by the Lie Punisher, and what that entails.
(The player isn't told they are insane, nor is this part of the role card included. The player they target will actually be vanillaised if they tell the truth about their alignment.)