April 10th. The previous day marked the end of spring break, meaning today began as a school day. After being roused by his adorable younger sister, Itsuka Shidou assumed it would be just another ordinary day. As for foreseeing the chance encounter with the girl who identified herself as a spirit... Accompanied by a sudden shockwave, the cityscape disappeared completely. In a section of the street that had transformed into a crater, the girl stood there. "—You, have you come to kill me too?" She is the calamity destined to wipe out humanity, a monster of mysterious origin, and an entity shunned by the world. There are only two methods to halt this girl: destruction, or dialogue. His younger sister Kotori, clad in a military uniform, therefore told Shidou: "Since it's like this, just go date her, and make the spirit fall for you!" "Wh-whaaaaaaaat!?"