It is the year 2096.

Almost a century has passed since magic was established as actual technology. A pair of siblings were about to enter the winter season of their second year in high school.

Tatsuya, the older brother, bears a fatal flaw in his magic abilities.

Meanwhile, the beautiful and intelligent, perfect younger sister, Miyuki, has unmatched magical talent. An irregular and a star student. Despite their differences, the pair of siblings were living alongside each other in harmony.

That is, until they received a certain letter...

 

The letter contained an invitation to the New Year's Banquet, to be hosted at the Yotsuba Clan's headmanor.

The Head of the Yotsuba Clan, Maya Yotsuba, and the heads of each family of the Fours will be in attendance...

There, the next Head of the Yotsuba Clan will be announced, and a shocking truth will be revealed.