Yeah. She'll have to project it into reality around her skin rather then it always being there, the longer she has it up the more strenuous it is, and right now she can only cover a small portion of her body with it. However, it is strong enough to deflect an attack or two no problem from even C ranked characters. She has the potential to get to rank S by the fourth year once she learns a proper fighting style, perhaps in a training montage by an instructor at some point and a whole lot of hard work.

Then maybe for the final boss she gets a sword and unleashes her kendo skills on him single handedly while using her other hand as a much larger and more powerful shield then she was capable of before.