Shinonome Yuya is a dropout from the elite school Yunagi Academy. She is Akari Hisatsugu, who is a loner just like him, but is at the top of her class. The two, who are polar opposites yet similar in some way, suddenly fall deep underground of the school and get caught up in the game of All Night School, the world behind Yunagi School!! The school of night that lasts forever. The reward for the game played in pairs is the mysteries of this world and memories of their own past!! Will they be able to reach the truth in this world?! A school suspense survival game where “trust” is the key!!