Adellein and Steizicka, the inseparable twins, decided to follow the steps of their parents for being detectives. Eager to enhance their skills, they entered the school Himitsu Academy, one of the most favored school for detectives. The name of the school itself hit the twins because of the meaning of it. Little they know that this Academy has really a SECRET. Would they find out what is it? Would they know why is it the most favored school for detectives? Well, let's figure it out!