Takeru Yagi lives a normal, average life. He lives with his adoptive father Rokunosuke, and eats breakfast with two neighborhood girls, the sisters Asuka and Kotono. Takeru attends a kendo club at school with his best friend and rival Takeshi. It's an idyllic, peaceful life, where the greatest drama is whether Takeru or Takeshi will represent the school at the kendo tournament. Then one day, everything changes. Takeru and his friends are transported to a world like their own, yet fallen to ruin and filled with monsters. Moreover, people in strange clothes are highly interested in all of them.