Decades have passed since the world became flooded with monsters. The protagonist, who enrolled in an academy to train those with aptitude, consistently ranked last in ability tests. It would have been one thing if his abilities were merely low, but because he also inflicted a debuff (ability reduction) on his surrounding comrades, he was called “unwanted” and a “burden.”
One day, while exploring, the protagonist is swallowed by a different dimension and goes missing. There, he encounters a creature from another world and is told the true value of his ability. Originally, magical power is something used to attack by projecting one’s own power outwards. However, the protagonist’s characteristic is the complete opposite of this “output”; it is “input” (absorption), and the ability to suck in external power is his true strength… “Reverse Magic Circuit.” The reason he had been debuffing his allies until now was that he had been unknowingly absorbing their power.
Having learned the true worth of his power, the protagonist now absorbs monster attacks to nullify them and gathers external power to strengthen himself, mastering his abilities and proceeding on the path to becoming the strongest.