Superpowers, well, those exist in every being, but they can be rather... weak. So, to get powerful -- I mean truly powerful -- one would have to call on the ones who gave the powers to begin with.
And with that ecstasy and strength that follows, there is an ensuing price that must be paid. The price, being rather extreme, forced the superhumans to adapt and create a way to stop these traumatic deaths, thus introducing an academy.
But the ones who gave the power, they want to see superhumans in pain and so they try to tempt these superhuman students. They fail often, but with the superhumans they succeed with, it leaves them smiling.
And once they have a grip on this superhuman, the process is irreversible, unless… there was someone who reached to the power beyond them.
