Once upon a time, there was a war between the Imperial army and Ninku, an elite unit of 12 zodiac warriors led by their master. Just when the Ninku were about to win the war, their master asked them to hold back and disbanded the unit. The series follows the adventures of 3 of the 12 zodiac warriors, along with the sister of one of them and a penguin, and the repercussions of that fateful day. It is a journey of friendship, loss and adventure, as they run away from the Imperial army who are trying to eliminate them.