Bundled with the twelfth volume of the Devils' Line manga, this OVA finds Yuuki Anzai visiting his mother, Midori, who finally tells him the story he's never heard: how she met and fell for his father, Tamaki, twenty years earlier. Framed as a quiet family flashback rather than an investigation episode, it fills in backstory the TV series only gestures at, and assumes viewers already know Yuuki's situation as a devil-blooded police officer.