Monsters known as Calamities have invaded Earth, and humanity fights back using powerful abilities. High schooler Kouya Kamigami is considered useless because he was born without a skill in a world where everyone’s strength is measured and ranked. But everything changes when a near-death experience awakens Mugen, the most powerful Calamity in history, within him. Thanks to this, Kouya gains a powerful skill, but Mugen remains inside him, waiting for a chance to steal his body for himself. Can Kouya become the savior he’s always dreamed of, or will Mugen succeed in bringing about humanity’s destruction? (Source: WEBTOON)