Is "Non Restraint Punishment" another name for "Mental Bondage"?
Whatever the name we may give to it, I really love this kind of games in which the Mistress makes us turn our great devotion to her against ourselves by ordering us to submissively collaborate on our own torture!

It usually consists of instructing us to take a position which makes us very vulnerable to a specific torture activity (with the targeted area brought to the fore and our free hands somewhere far from it) and to keep it whatever happens while she's frenetically torturing us.

Asking us to voluntarily give her full access to our most sensitive parts (typically nipples, balls, ribs...) and to stoically endure this pain from and for her without moving is a good way for her to "test" our devotion and obedience in a sadistic way. Although the sub isn't actually tied and could easily stop the torture by protecting himself, would he really dare to disobey and disappoint his Mistress?

Alternatively to keep them immobile, she may also order us to use our hands to do something else while she's torturing us, such as untying knots on a rope, preparing coffee, massaging/caressing a part of her body, or finishing ourselves if it is the end of the session. (I have already be subjected to each of these little mental bondage games and each time it was great!)