Shiro is the son of Ryoma, the cousin of Kiragi, the grandson of Sumeragi and Ikona, and step-grandson of Mikoto. In his Paralogue, Shiro departs from his Deeprealm and ends up in a barren desert in the real world. Upon entering, Tarba ambushes him and threatens to kill him if he does not give up his equipment. Shiro refuses and prepares to fight Tarba and his gang despite being vastly outnumbered. Fortunately, Ryoma and Corrin's forces arrive, after receiving word from Shiro's caretakers that he had gone without a trace. Ryoma is upset that Shiro left his Deeprealm, having not been taught anything about the real world. Though he suspects his father his royalty, he confuses his title as the "Big Cheese" of Hoshido and is soon confronted by Tarba, who demands him to give up his equipment or die. Shiro refuses and prepares to fight Tarba and his gang despite being vastly outnumbered. Following the battle, Shiro learns from Ryoma that he is actually royalty, though he is angered that Ryoma had kept his identity a secret. Ryoma tells him that he did not reveal it because he felt that he was not mature enough, though Shiro states that if he had known, then he would have tried harder. Shiro also admits that he is scared because he had been taught how to fight, but not to kill. Ryoma admits that he was wrong in concealing his identity, but asks Shiro what he observed in the fight. Though hesitant to succeed Ryoma as he grows, Shiro decides to join the army to learn more about his father and the role he plays in protecting Hoshido.