The Phoenix Empire has finally made peace with the Khas Kingdom. In honor of this, a great feast and a ball were called. The nobility and the royal family from both sides are invited. King Arthur Rowan loves his son Alto very much. The King has hired "Eclipse", the most famous mercenary in the world. He didn't expect the "Eclipse" to be a girl named Yuniko. No one except Rowan's knows that the famous mercenary "Eclipse" is a girl. Alto Rowan is kind, smart, funny, muscular, strong and playful.