Who was the emperor while Prince Sanjō Sanetomi was an Imperial court noble? 
Meiji Restoration: The Meiji Restoration (明治維新 , Meiji Ishin ) , also known as the "Meiji Ishin", "Renovation", "Revolution", "Reform", or "Renewal", was an event that restored practical imperial rule to Japan in 1868 under Emperor Meiji.
i don't know