Konketsu no Shoujo

Half-human, half-demon. That's what Tanaka Yumi is. After being expelled from her previous school when she lost control of her demonic powers, she transfers to St. Ishiyama, at the same time as two particular Pillar Generals. When she becomes the prime target of a group of assassins, Hecadoth promises to help her control her powers so she can fight back, and open up to others.