Ai Anju is a typical 13-year-old teenage girl with a twin brother named Yuu. The story starts when they both turn 13. Ai-chan is a healthy lively girl but her brother was born with a heart defect. There are hardly any boys born in the Anju family and if so they are usually very ill

Ai-Chan's mother died short after her birth. Besides her brother Ai-chan has two more siblings - two girls Hoshi and Hana. The only thing known about her father and grandfather is that they are long dead.

The story begins with a misfortune; Ai and Yuu's grandmother dies one day before their birthday

Ai-Chan learns about the family secret from her oldest sister Hoshi. Everyone in the Anju family has a certain Gene- sequence in their DNA known as the "witch-sequence" Through this DNA it is possible for a girl to become a witch. With the help of a perfume bottle, which has been in the family for ages, Ai-chan is able to wake her powers. After one fulfills the ritual successfully one becomes a witch. One can also decide not to fulfill the ritual thus one stays a "sleeping witch" without powers

To fulfill the ritual Ai-Chan must sacrifice her "Dearest" She must be willing to trade her greatest treasure in return of Witchcraft. Ai-Chan doesn't know how to decide, because to her Yuu is her greatest treasure. Loosing him? That she couldn't imagine. Ai-chan is completely confused. How will she decide?