Rein was the third and the oldest of two farmers: Lightning and Sa-ven. Lightning named him after the Rain from the Sky in hopes he'd grow up to spread his beliefs amongst the world. As a child Rein grew up fairly normally with a family that had been very close. His brothers and him all trained to become renknown shinobi in secret in the future. Rein would work on the farms with his parents more than his younger brothers would have, only because he had been the oldest. Sa-ven wanted the boy to grow up to be the best farmer there had been, providing for Konohagakure. Rein disliked this idea, and is the reason behind why he trained in the arts of the Shinobi in secret with his brothers. The boy would soon grow to greatly dislike his father, seperating the bond between their happy family. With the thought of not wanting to follow in his father's footsteps, Rein ran away from home...
Now living in the forest for over two years, Rein finally returned to his home Village; 'Konohagakure,' to find out that his entire family had been killed in a raid via opposing Shinobi of other Villages. He gave little dwell on their death but more action to do something about it. With another year of training, Rein would have soon joined the Academy in thoughts of doing what his brothers and him intended to do; Become reknown Shinobi. Within a few months of joining the Academy, Rein had learned all there was to learn in this area of his life, soon graduating weeks after to become a Genin during a war against Kirigakure. With the Village at great stakes, Rein was quickly put into Squad Oyashiro to help guard the Village and in case more units were to deploy. The boy had become greatly noticed by Oyashiro when he stood to ask him for training in the arts of a Medical-Nin; hoping to beable to heal and rescue those on the near-death trail.
From a child up to this day, Rein has always been a very kind and joyful person. His nindo way, "If you have a dream you want to make a reality, then it isn't a dream... it's fate." leaves his mind to explore in wonders, hoping to gather as much information as possible so when an obsticle arives, he'll be able to accomplish it.