Set in the tumultuous Warring States period of Hinomoto, the uncharted Kinokuni region boasts both mountains and sea. Deep within its dense forests, a group known as "Saikashu" brandish guns and fly the "Yatagarasu" flag. Magoichi, a foreigner, has taken the helm as leader of Saikashu. Meanwhile, Saburo is quick to sense the looming threat posed by European military forces, and strives to defend Hinomoto. As fate would have it, the two unlikely allies will find themselves thrust into battle against foreign invaders!