The younger 11-year-old stepsister of Sora. She has a pristine and composed appearance, but, like her stepbrother, has a perverted side as well. She is quite cute, described by Sora as having a "perfect, flawless beauty". Though younger than Sora by 7 years, she holds just as much influence in their relationship as he does, regarded as his equal, if not his superior. She is very attached to her brother, and unwaveringly trusts his abilities and decisions. She has resolved to always follow him no matter what, and likewise, Sora promises to lead her to greatness.
A born genius, Shiro is good at anything that involves calculation, and is capable of speaking over 20 languages and learning a new one within 15 minutes. She is excellent at playing chess and FPS games, but has trouble dealing with matters related to deceit and strategy. After winning the king election contest with Sora, she becomes the queen regnant of Elchea. Shiro is determined to stay by Sora's side and together with him, conquer the world and challenge God. When she is not with Sora, Shiro becomes incredibly despondent and unresponsive due to her anthropophobia.