Rin (Protagonist) won't lose something so precious so easily.

"This thing is great!" You think to yourself as you come back down from having your mind blown. Device in hand you turn it over a few times thinking to yourself, "I can't let this fall into the wrong hands," and you shudder to think what Sasuke, or Katsuki and their tempers would do, or Minoru who, while you may be able to respect his perverse drive, lacks any tact and would likely just just make himself that last penis on the planet. Not a bad idea actually, but first to make sure that if someone does become the sole bearer of meat, it will be you. Quickly your fingers begin to hammer at the keys to write a new reality.

First: Rin Nakiama is the sole possessor of the reality warping device. In fact, the device is physically part of her, and is seen by the world as her (Primary) quirk. She is the only one who can use it.
(That should make sure you can't lose it, or have someone steal it from you)

You hit enter and your room glows. When the light fades you are no longer holding the reality warping handheld but instead are looking at a screen that is part of the inside of your non-dominant wrist fingers on a set of keys below it.

Second: Rin Nakiama can choose whether or not others recognize the changes in reality that result in the use of the reality warping.
(Hopefully this will make it to where regularly using if for small stuff will result in people believing there to be limits to what Rin can alter, and draw less attention to her using it, so that people aren't constantly paranoid around her that she might have altered them.)

You press the button to confirm the change and you feel your fist clench as it begins to release the red glow. Instinctively you know that this is a feature that came as a result of the first change you made just now which will allow you to alter the shape, targeting, and directionality of the changes you are making if you don't want them to be universal but instead want to control who/what gets effected. Also instinctively you know just releasing your grasps makes the alteration universal which you do.

Third: Rin Nakiama is a...

A knock on the door to your room signals that you mother has returned. There is a panic that sets in, you made it to where she wanted to give you a blow job to apologize that doesn't necessarily mean she wouldn't have regrets about it only to take that out on you, for "letting her do it".

You begin typing something in panic.

Your mother's voice calls in as the door nob begins to move, "Rin what have I said about using your quirk in the..."

The red flash glows and dims as you fire a laser of the red energy into your mom as she peers in from behind the door.

Third: Is completely submissive and supportive of Rin Nakiama