As the name implies, "Aho" Girl, or Dumb Girl, is as stupid as you can get. Which is why her crush and childhood friend, Akuru Akutsu (or "Akkun" as everyone calls him), isn't the only one unwilling to put up with her fallacies. Along the way, they are joined by many other fellow idiots as they probe deeper into the true meaning of idiocy, and the true relationship between Yoshiko and Akkun.