Kamen Rider Blade

Ten thousand years ago, a massive battle known as the Battle Royal was fought by fifty-two demons known as the Undead, each representing a species fighting for dominance over all others. The winner was the Human Undead, known as Category Two of Hearts, giving dominion of the Earth to humanity. In the present day, archaeologists discover the sealed Undead, and accidentally set them free. Thus, a new Battle Royal begins.