The beautiful witch chocolatier Aikawa makes a mysterious chocolate that makes your wish come true just by eating it. One day, a high school girl who attends Seiran Gakuen visits Aikawa. The high school girl is told a dangerous contract that "a person who eats chocolate will be deprived of his" most important thing "as a substitute," but she accepts the contract and eats the chocolate. And from that day, mysterious incidents happened one after another in Seiran Gakuen ... On the other hand, Nao Iida, who belongs to the newspaper club of the school, follows those cases. Nao approaches the dark desire hidden in the incident and the mystery of chocolate.