Long time ago their was a ninja known as Itonami, he created the Souseiki lab which was well known were the best medics around the world go to learn medical justu later on that year he chose 10 ninjas to join each of his units. The Souseiki unit and Itonami unit which both were different units at the time who soon realize at the end would have a war with their creator. Knowing they would be sold as slaves.