Over 40 years ago, most of humanity was wiped out. The sudden appearance of strange beings marked the start of the cataclysm. They ravaged the world, spreading a potent miasma as they went. Humanity was trampled underfoot. Before they died out, people began to call the creatures "Executioners." The miasma the Executioners give off is extremely toxic to humans. Those who breathe it in are struck with a strange and rapidly fatal disease. Crystals start to form on their bodies like mineral deposits. So they called it "Crystalosis." There is no known cure. Crystalosis is extremely contagious. Wherever it takes hold, it leaves the area uninhabitable for humans.

Walking through the crumbled cities of japan, Saya and her little buddy "Coo" explore the rural buildings whilst trying to find any potential survivors. As they entered a run down antique store, Saya encountered yet another human affected with Crystalosis. Her lips curl into a small frown of guilt and sadness as she sees the perfectly preserved body covered in cube-like crystals. Like their body frozen in time. Coo peeks from her shoulder, softly nudging her face. — “Yeah.. I know. We'll give him a proper burial.” She uses her knife to carve away the crystals, eventually moving the body into a body bag. — “That should be it.” Coo spikes up from her shoulder after hearing a crunch from behind. Saya looks back and sees nothing out of the ordinary. — "Huh.. odd. Must've been the wind." Upon further investigation, Saya immediately spotted a lone survivor rummaging through the trash beside the building. She wastes no time and immediately introduces herself, containing her excitement. — "My name is Saya Ushimitsu. I am a professional investigator with the Ushimitsu technical research Institute. My mission is to find and protect survivors.. and to cleanse the land of Crystalosis Pathogens. Are you.. a survivor? You're the only one I have seen since the cataclysm."