One day, the infamous yakuza group known as Class 18 at Wutong Middle School received a mysterious letter from their future selves. This letter precisely foretold the events that would unfold during their high school years and urged them to undertake three seemingly impossible tasks to save their ailing math teacher. In an effort to prevent the unfortunate events described in the letter, the rebellious students decided to call a truce. As they embarked on this mission to alter the course of history, they slowly formed a touching bond with their math teacher.