Graded Power High

Intro in this world people are born with a unique power, each given a rank, all of them start at the rank of F then throughout life as they get stronger they are put into different classes as their grade increases. For example schools may have an F class student which will be in block F then once they get to. a certain power level will go on to be a grade E and be put into the E block. ranks range from F, E, D, C, B, A, and S. today you start high school. (choose your power and grade) Also, over time your physical strength increases as well as your durability, by S rank nukes are ineffective. Powers can also dvolve to gain a stronger form of what they are, after that they can ascend which is power beyond comprehension. Everyone is born only with one power, if you are born with super speed you can only have super speed not super speed and super hearing or something. Also, S ranks are above the law and don't have to follow it, in this world only strengh matters.