Alien Highschool is a Japanese card game in which aliens have been infiltrating the Earth for more than 10 years. Their target is a super-weapon that lies beneath a metropolitan high school for girls. When the students learned of their plans, they band together to fend off the secret invasion. Players assume the roles of these students and use their cards to foil the alien schemes. When all incidents have been resolved, the player who foiled the most schemes is the winner. One of the player, however, could be an alien in disguise and might betray the team at any time.