User blog comment:Imouto-tan/Nayuta Mitsuari/@comment-4867780-20170619214129/@comment-26362471-20170619234717

Nayuta leaves them on to reassure the Grand Magic Council that she is not against them, however, there are times when she unleashes her full power to help others. I.e. To keep Amatsu-Mikaboshi sealed within her body, which in itself is pretty draining since he keeps trying to escape.

She, like all of the Wizard Saints, is always under close watch by the 13th Squad aka the Saint Killers to make sure that she doesn't betray the council and undo the seals. Her house is located in a heavily surveyed area with at the least 500 active guards 24/7 due to it begin near a Council members residence.

Ultimate Liar is rarely in use because she has the Magic Apps and her kunoichi skills which are much more useful in combat than trying to make up a good like that can stop all.