Maou Mara Bonnou Gakuen ~Yuusha, Kyoushi ni Otosareru~

In a world overrun by mysterious monsters, humanity creates enhanced warriors known as Heroes to fight back. At the Hero Academy, sisters Sakuya and Kaguya train together to protect humanity. However, they are captured by the Demon King Mara, who begins a twisted plan to corrupt and reforge them into his loyal followers.