Yumego No GureiBougo no Grey; 夢後のグレイ; It's Grey after the Dream Ends.

3 years after the war. The war volunteers still haven't gotten their normal lives back. Known as the "Assassin of Adenzi", Ef, the girl who was feared on the battlefield, had been spending her days with nowhere to go. A certain missionary reaches out to her. The look in her eyes is suspicious, and warm. "I will make you happy. I promise..."