The wind, carrying the heat of summer, swept across the clear, blue-green sea, stirring up waves no one noticed. The water rose and fell, and the sound of the surf gradually rang out, sweet and melodious.
This was the Pacific Ocean, the largest, deepest, broadest ocean in the world, with more islands than any other.
At the very center of this vast ocean, around 330 kilometers south of Tokyo, floated an island.
It was an artificial island.
However, it was by no means an ordinary artificial island.
Seen from above, people could only make out a city filled with towering steel buildings, sitting upon the ocean and forming this enormous metal island.
In reality, the island had been constructed from carbon fiber, resin, metal, and magic, all joined together by colossal floating structures.
The temperature here stayed above twenty degrees year-round, and its total population was approximately 560,000. Administratively, it belonged to Tokyo Metropolis, but in reality, it was a special administrative district with an independent political system.
The purpose of this administrative district was to protect nonhuman lifeforms on the verge of extinction and study their bodily tissues and special abilities.
However, the so-called nonhuman lifeforms did not refer to animals, but rather—to "demons."
Countless lifeforms existed in this world that could otherwise appear only in myths and legends.
For example, beastmen.
For example, elves.
For example, monsters.
And then there were vampires.
At Chaldea, nonhuman lifeforms like these were called Phantasmal Species. Though they had nearly vanished in the modern era, in this world they had survived and were known to the public.
Naturally, magic, sorcery, and all kinds of other mystical systems also existed here. In terms of the purity, advancement, and prevalence of the mystic arts, this world far surpassed all the others.
Thanks to this,