Ou Imouto no Brunhild

A hundred years have passed since a member of the Siegfried family was born with the Power of God. To maintain their rule, the royal family sends children to a secret lab at age eight for painful procedures meant to trigger the power. Sigurd, the heir, undergoes the treatment with the hope of sparing his younger sister Brunhild from the same experience. He returns three years later with the Power of God, but he is now a violent, amnesiac version of himself. Sigurd grows resentful of Brunhild and exiles her, but recalls her when she herself awakens to divine abilities. Now married to her brother, Brunhild must navigate the dangerous situation to ensure her survival.