It's Grey after the Dream Ends.

Three years have passed since the war ended, yet the volunteer soldiers still struggle to reclaim their ordinary lives. Among them is Efu, once feared on the battlefield as "Adenzi's Killer," now wandering with no place to call home. One day, a missionary extends a hand to her. Her eyes are both enchanting and warm, offering a comfort she has never known. "I will make you happy, won't I? No matter what…" Is her kindness salvation or something far more sinister? In a world that has yet to heal, Efu must decide whether to trust the woman who promises happiness—or to keep running from the ghosts of her past. https://www.cmoa.jp/title/338267/