In this world, people belive that every 3rd child someone has is bad luck. And if you happed to have twins as what was supposed to be a 2nd child-one that came out 2nd is(making them 3rd) bad luck. Same goes if you have triples or quadruples ect as your 1st kid. Shiro was one of those kids. Those kids are usually eiter abandoned or sold away to slavery and in some cases even enslaved by their own family. This is not something that they wait for-they do it as fast as possible. And they did it with Shiro when he was only 2. He was named "Shiro" which means "loneliness", constantly reminding him that he will always be the black sheep and never actually focusing on positive meaning of the word-"white". Kids like this were often mistreated and hurt and even killed, so they tried running away, but they were marked by burn that makes number "3" on their arm and they often didn't last long before being captured again. Shiro is 4 now.