Yagi Takeru has been living in the Touma family house since his parents passed away. Raised by Touma Rokunosuke, the head of the household, he is surrounded by friends such as Yamato Takeshi, his best friend and rival in the kendo club, the Shiratori sisters Kotono and Asuka, and his childhood friend Oosu Seri. Life is blissful until an earthquake strikes the school and everything changes. Takeru awakens to find the school reduced to ruins, as if abandoned for centuries, and discovers that all teachers and students have vanished. He meets Seri and Asuka, and together they flee the wreckage, only to realize that the town they once knew is completely…