Daichi attends Yakumo Academy with his sister Misora and childhood friend Honami, and is part of the local history research club. One chilly autumn day with the annual culture festival fast approaching, he was spellbound by a girl in the hallway who had very abnormal looks. Her hair was bone white and her eyes were blood red. She vanished an instant later like an illusion. He met her again the next day and was dragged into an extraordinary world.