How real is Shōgun?

Shōgun, FX's period drama-action series on Hulu, has drawn comparisons to Game of Thrones, thanks to its shocking violence, like people pulling out their own guts with swords and others being boiled alive slowly. Unlike that brutal flight of fantasy, however, Shōgun is based on the 1975 historical novel of the same name by James Clavell — which was inspired by true events during the late Sengoku period (1467-1615) in Japan. In other words, there's something real to this horror. This time was ripe to be fictionalized, defined by civil wars among different liege lords across the land — called…