The World of Elements
There are three rules in this world.
Rule 1: Everyone is the physical embodiment of their ability.
Rule 2: You cannot use your ability if people are witnessing it.
The exceptions to rule 2 is a) you get into a fight you can use your ability, or b) the world permits you to use your ability.
Rule 3: You cannot die.
This is story of those whose abilities are strongly linked to their emotional well-being, and must fight if they hope to escape their spiral into madness.