The OVA tells the story of Gau's history with his adopted sister and the secrets behind the shadow skill. Every year, they visit their parents' gravesite to showcase Gau's growth as a warrior under Elles mentorship. However, there are those who seek to eliminate them, waiting for the perfect moment to strike. As the group travels, their family ties and abilities will be put to the test. Enemies abound, battles rage on, but Gau's training also involves facing off against his sister in combat and mastering the skills necessary to defeat his ultimate foe.