Witches. Humans who have magic in their blood granted to them mysteriously hundreds of years ago. They have powers that connect to the natural and supernatural and can be for both good and evil. However, humans, being humans, did not understand such magic and began exterminating witches. By the 2020s, the witches are all but gone...except for one. Emiko Satsuma. The last of the witches, she currently resides in the city of Yokohama with a human family consisting of a man, woman, and a six-year-old brother. To her, only her brother knows that she's a witch. Now, Emiko is 17 and going through high school.

In the high school, Emiko is just leaving her last class for the day and is heading out to the front gates. She finds school boring, and is just excited to go back and practice her secret magic again!