Ajimu is really mostly hype at best.
There are many characters in obscure fictions on the fringes of the internet that transcend 10 dimensional being and transcend infinite cosmic floor dimensions, and possess infinite number if powers, and possess powers that don't even exist yet, that are totally oblivious and inapplicable to the concept of them or any part of them including their powers of "being erased" since they constantly erase themselves and restore themselves like nothing. The worst part is, they are the lowest tiers in their fictionverse and are already countlessly above Ajimu. Ajimu is in really FAR from being "complete" arsenal. It is nothing more than a title applied to someone that theoretically isn't what you call it.
You'll fine that some other characters possess powers that cannot be comprehended and one cannot use human tongue to describe it at all. That just describing the powers would destroy any hyper dimensional who listens to the user describing it and using a "higher" language to describe the powers. The user can already destroy anyone and distort anyone's being by just describing their inconcievable powers and are literally that powerful that they possess powers that already have effect by just language without even using it. That is already far above the level of anything Medaka Box has offered.
Who says barriers are the only obstacles to solve? Some fictional characters even embody whatever it is you want to do to them and it is totally inapplicable and don't need freaking barriers to defend themselves. You need a true omnipotent to "kill" them.