The 16-year old head of the Hadou Financial Group, Ruri wields considerable power in Arkham City. After her parents were assassinated by agents of the Black Lodge, she was taken care of by her grandfather, Kouzou Hadou (覇道 鋼造 Hadō Kōzō?). She cared deeply for him and sought to live up to his legacy by piloting Demonbane in battle. To this end, she employs Kurou to search for a suitable grimoire, but circumstances place the controls in his hands instead. Though she is initially bitter that someone outside the Hadou Group is piloting her grandfather's legacy, she swallows her pride and directs Demonbane's support crew from an underground command center.
In her own route, Ruri comes to depend on Kurou more as time goes on and eventually realises that her resentment is unwarranted, given that she is not suited to front line combat. After he is injured defending Arkham's underground shelters from the Black Lodge, Ruri makes a contract with Al and attempts to fight in his stead. Although she is still no match for the Anticross, she is instrumental in resuscitating Kurou and tipping the balance of the battle. Before Kurou pursues Master Therion, she confesses her love and promises to wait for him to return, though for a whole year there is no news. Unbeknownst to her, Kurou is defeated when Nyarlathotep is able to exploit Al's growing jealousy to distract her at a critical moment. Al is still able to cross time in order to give word of his last moments to Ruri, but she refuses to accept defeat and renews her contract, which draws her through dimensions to the scene of the final battle. With her help, Kurou is able to defeat Master Therion and restore the timeline to its proper state. Since the Black Lodge is erased from history, Ruri loses her memories of the story. She decides to attend Miskatonic University and ends up meeting Kurou again, while Al watches on, accepting that she cannot be together with him.
Ruri generally coordinates the efforts of Demonbane's support team, consisting of her personal maids, Makoto, Sonia and Chiaki, from their secret underground base. As the head of the Hadou Financial Group she possesses excellent leadership and organisational skills. When she makes a contract with Al, she gains the ability to transform into a magius and has all the same abilities as Kurou, though she has no combat experience. Ruri proves unable to wield the Scimitar of Barzai with one hand, for instance, and generally uses either Cthugha or Ithaqua but not both. She is also capable of piloting Demonbane.