Mother struggles with a cruel past. The son is trying to accept a cruel future. The father does not see the danger hanging over them. High on a mountain on the edge of the Kaigen Empire live the most powerful warriors in the world, capable of raising the sea and fighting with swords made of ice. For hundreds of years, the fighters of the Kusanagi Peninsula drove off the enemies of the Empire, giving the name to their piece of land - “The Sword of Kaigen”. Mamoru was born into the legendary Matsuda family, and he always knew his goal: to master the techniques of the battle of the seven and defend his homeland. But when a stranger arrives and reveals the truth about the supposedly peaceful time in Kaigen, Mamoru realizes that he may not have enough time to become a full-fledged warrior. Worse, the empire he was born to protect may be founded on a lie. Misaki told herself that she had left the fervor of her youth behind when she came into the Matsuda family. Determined to be a good housewife and mother, she hid her sword and all that was left of her days as a fighter in a distant land. But with her growing son asking questions about the world outside, the threat of invasion looming over the sea, and her cold husband irritating her, Misaki discovers that the fighter in her is trying to fight her way to the surface. When the winds of war blow to their peninsula, will the Matsudas be able to defend the empire? Or will they tear each other apart before the true enemies reach their shores?