Sai was conditioned to remove all emotions and as such, had difficulty connecting with others. He has a brother names Shin. His social ineptitude tends to get people angry. He often speaks without considering his words and their effects on people. Sai is very observant, and is always focused on his missions. He pays a lot of attention to detail, allowing him to quickly notice if something is not as it appears. Sai has short, straight black hair, and dark eyes, with very pale skin.