Kurenai Gekkou, a freshman and also the student council president of Miyasaka High, is a self-proclaimed genius. Nine years ago before the starting timeline of the story, due to a certain deed committed by his younger twin brother, Hinata, Gekkou was prompted to constantly seek out power, initially driven by the fear for his life, and later motivated by the prospects of revenge. Gekkou is demonstrated to be quick-witted and highly intelligent. He wields an ancient fencing-like sword known as Spell Error, and is trained in several traditional arts of exorcism. As the student council president, he has made a contract with the lightning demon Mirai and is tasked to be the guardian of the Holy Ground. He claims Mirai as his property and is very possessive over her.
Source from Wikipeida