In this OVA, Gau's intricate history with his adopted sister unravels alongside the mysteries shrouding the shadow skill. Returning annually to their parents' gravesite, Gau showcases his growth and prowess as a warrior under Elle's guidance. Despite his significant progress as a Sevalle, dark forces lurk, plotting their demise. Embarking on a perilous journey, the bonds and abilities of this family will be put to the test. Facing numerous adversaries in intense battles, Gau must also confront his sister in combat, embracing the necessary skills to overcome his ultimate foe.