Zelk the Lord of Dark Flame

That day, the sky split and the world collapsed. Nekohana Natsuki, who was standing directly beneath the rift, blacked out. When she came to, five years had already passed. Civilization has crumbled, and monstrous beings known as igyou prowl the ruined earth, preying on humans. When Natsuki is attacked, a strange voice speaks inside her head: "Use me to your heart's content. Reduce everything to ash. My black flame." Thus begins the journey of the world’s cutest boy across a devastated world!