Angel Core: Tenshi-tachi no Sumika Episode 1

One war is over, and another war is about to start... A young military officer, Captain Ralph Maskenval, was sent to Nortland, to fulfill a mission, which was to keep a close watch over the Angels. The Angels were coerced into believing they needed to have sex to nurture the "Angel Core" inside. Ralph starts to feel awkward about his mission. Then Ralph learns the reason behind the Angels' sex-craved behavior. Ralph will have to make a big decision...