Owari no seraph:The Half Humans {editing/continuing}

What if there were survivors who became there own army like The Moon Demon Company. They had demons as well but stronger. They have better technology. And they hid from their part of the seraph of the end project. This would be the Human Demon System in the Chinese Half Human Army.
Two sisters who been side by side since they were little, work in the system.One sister named Mari Ann who was the older sister and the other was named Arosa Ann meet the Moon Demon Company and make peace. After learning each others pain and differences,Mari finds out what they were working on. And faces them to stop them from making the world worse than it is. But one thing stops her. She starts falling in love with Guren,even though she was just suppose to spy on them and kill them if necessary. But Mari hides something very dark about herself from JIDA, especially Kureto since he wants to use her for experiments. While Arosa also spies on Yuu for his strange sense of power,but starts having feelings as well. What will these Sisters do?
I DO NOT OWN OWARINOSERAPH OR ITS CHARACTERS!!! I DO NOT OWN ART OR VIDEOS!!BUT some scenes in the anime will be in this fanfic book. I hope you enjoy it.....