[Anime Crossover+] Glazed Crimson (Descent into Darkness)

Novels, manga, and an army of three thousand transmigrators rampaging through them. Every transmigrator is exceptionally skilled and flawless in appearance. As one of them, she has one or two strong suits of her own. But after her predecessors and successors have swept through like locusts, every world has been thoroughly wrecked. Serious dramas, subversions, comedies, awkward farces, snark, total breakdowns, harems, and everything else have all played out. Now it's her turn, but being a transmigrator isn't any fun anymore. What should she do? After much thought, Lubi decides to accomplish something groundbreaking while she still has time. Kill them all! (A story about a chuunibyou going dark and fulfilling her duties as the great demon king bent on destroying the world. Enter at your own risk.)