An unknown plague called the "Doomsday Virus" suddenly appears in the world. Those infected will die of organ failure within 72 hours. The only antidote is hidden in a weird "survival game system" - a transparent scorer will appear on the wrist of each selected person, showing the "survival score". Points are obtained by completing various survival tasks, and every 1,000 points can be exchanged for an inhibitor that is valid for 24 hours. Once the score reaches zero or the inhibitor is not injected on time, the virus will explode.
What's even more cruel is that this system is only activated in specific areas – randomly selected schools across the country. The heroine Jin Miaomiao lives in Class 7, Grade 3, No. 1 Middle School, which happens to be the only "playground" in the city.
