From MangaHelpers:
A class is chosen to participate in a special government project, designed to reverse the trend of declining academic ability in the younger generation. They head out together to an unusual school camp. The students know nothing about what the program will entail, and are surprised to find that it involves playing a class-wide game of a modified version of "Old Maid," with the joker as the losing card. There are incredible incentives toward winning the game, but the penalties for losing, or for not playing at all, are correspondingly severe.