Balsa the spearwoman is a wandering warrior, who takes on the task of saving lives, in atonement for a past sin. On her journey, she happens to save a prince, and is tasked with becoming his bodyguard. And he is going to need one, for his own father, the emperor, wants him dead. Throughout the story, Balsa's past will come to light and they will uncover mysteries about Chagum's condition while developing a family-like relationship with each other and others.

The heroine Balsa is a skilled bodyguard and a masterful spear-wielder. One day she rescues Prince Chagum who has fallen into a river. The prince is carrying a mysterious spirit egg in his body, and is in danger of being assassinated by his father, the Mikado, who fears this will damage his imperial prestige. Balsa embarks upon a perilous journey when she accepts the queen’s plead to protect her son from her husband.