Espers are the ones with cool powers but as they use their powers, toxicity builds up. Enough toxicity and they get close to rampaging. The usual signs are change in eye color(usually golden) and disturbing energy/aura. When they rampage, their powers get out of control and/or their bodies can't handle the surging energy and they die. Guides help get rid of that negative energy and toxins. I think of them like batteries that help espers recharge.
MC's previous esper used up too much of their power without guiding and died. The current group are a s-class group pretending to be c-class individuals to achieve a certain goal: open and conquer the SS class dungeon.
Can someone explain to me this guideverse..? is this eye condition thing a common thing in these verses? and what is actually going on with MC's previous esper and the current group...? things just dont make sense to me at all TAT