Legend speaks of seven heroes, each one bearing the power of one of the stars of the Big Dipper. Two of these stars are constantly in conflict, destined to battle and throw the world into chaos... Not that Taitou has ever paid much attention to old stories. Headstrong and defiant, he is the last in his village to complete his coming-of-age ceremony - a fact his sister Laila incessantly teases him about. When he is finally deemed worthy, he is presented with the Kenkaranbu, an ancient sword that can only be drawn by a true hero. As the frustrated Taitou struggles to unsheathe the sword, a mysterious thief appears, making off with the blade and citing the legend of the Big Dipper. The stars have been set in motion, as Taitou sets off after the Kenkaranbu and the truth of his own destiny... Hiromu Arakawa, creator of Fullmetal Alchemist, brings the legend to life!

With the Imperial Army in hot pursuit, Housei leads Taitou and the others on a little detour to the home of his master. But the "mean old devil woman" he had described turns out to be nothing of the sort. Master Kouei is a veritable font of wisdom; in addition to knowing a more covert route into the capital, she is well versed in the legends of the Hokushin-Tenkun. There is much she can teach Taitou as he struggles to control the overwhelming power of his star, but will she have enough time to impart her wisdom before tragedy strikes?

Ryuukou's warning still ringing in his ears, Taitou hurries back to Taizan, only to discover that the Genrou-tou has left his hometown in ruins. Though Taitou is devastated by the loss of his father, the attack has given him a renewed sense of purpose. Unless General Keirou is stopped, countless families and towns will face similar destruction. Meanwhile, back in the capital, Keirou's plan for seizing power from the emperor is well underway. With Keirou as the new commander in chief and Taigatei in prison, can anything stop the general's reign of terror?

The time is drawing near when Taitou must face the self-proclaimed ruler of the Ken Empire, Keirou - and the avatars of the opposing stars Hagun and Tonrou will decide the fate of the world! Taitou makes his way to the capital with only a handful of friends and Divine Warriors. With Housei gone and Rinmei in no condition to fight, the challenge will be even greater. But help may be found in an unlikely place: Ryuukou's loyalty strayed once, but he has returned once again to Taitou's side. There are still hard feelings, but Taitou will need the strength of all his friends if he wants to end Keirou's reign of terror!