From MangaHelpers:
In Meiji Era Japan (1884), art scholars Ernest Fenellosa and Okakura Tenshin opened a sealed temple that had been built 1200 years before. Inside, they found many swords and a bodhisattva statue wrapped in cloth. Why was this temple sealed in the first place? The truth lies back in the Asuka Period (645), at a time when there is political tension concerning the power of the Soga clan. Prince Naka no Oe is beginning to set a plot in action against the main branch of the Soga family, targeting Soga no Iruka.