After the murder of her father, Ryuuko Matoi has been wandering the land in search of his killer. Following her only lead the missing half of his invention, the Scissor Blade — she arrives at the prestigious Honnouji Academy, a high school unlike any other. The academy is ruled by the imposing and cold-hearted student council president Satsuki Kiryuuin.
Keita has two older step-sisters, Ako and Riko, but since they aren’t related by blood, they love him in a lustful way. After a mishap at school, Ako and Riko finally confess their love to him. Keita dislikes the thought of seeing them other then brother and sister, but as he tries to enter the same school as his sisters, he slowly becomes attracted to them.
A Knightmare unit made of boys and girls from Zone Eleven are thrown into a military operation with a 5% chance of survival. They must rescue an allied unit left behind on the European warfront. Among those selected for the rescue operation is Lieutenant Akito Hyuuga, known as “Hannibal’s Ghost” due to his prowess on the battlefield.