Chisato and her kendo-instructor brother Chitose are ordered to attend Nisshin House, the school for the Aizu clan — a place that has never had a female student. Despite the resistance, Chisato deepens ties with her childhood friend Mineji, the cheerful Matahachi, the serious Gisaburou, and the gunnery instructor Towako. She also meets Koutarou, who owns a clothing shop in the castle town, and Narihira, a young man of uncertain purpose. The fragile peace does not last. When war finally arrives at Aizu, the boys of Nisshin House are called to the front as the Byakko Troop.