When the world is struck by a deadly pandemic that turns humans into zombies, Takashi Komuro and several of his classmates at Fujimi High School try to survive the apocalypse.

A second-year high school boy finds himself uneasy during Christmas time due to an experience in the past. However, this year at Christmas, he gets his last chance to ask out a graduating female senior named Haruka Morishima — or one of several other classmates. The story of the anime will be arranged in an omnibus format, with each heroine getting her own version of the story animated. Each heroine will sing her own version of the ending theme song.