Arata Akihiro, an introverted high-schooler, was transported to an unknown world called Zemuria along with his classmates. In that world, the only way to return to their original world is to play games. However, if they fail to complete the objective of the game, they will have to play a penalty game, and failing to complete that penalty game will result in their death. There are 12 classes in total, summoned in that world and were assigned as classes naming in 12 zodiac signs. But by their cruel fate, they were assigned to the lowest ranking and weakest zodiac sign. How will Arata Akihiro survive in this harsh world called Zemuria...