I don't know much about Japanese horror historically, but I did watch both movies from this week's TCM imports from Nobuo Nakagama. I especially enjoyed the 1959 Ghost Story of Yotsuya.
The idea that the ronin (or samurai without a master, as I understand it) committed such atrocities against his faithful wife and her family, and just about everyone else he met was particularly interesting to me because he seemed to have totally lost his moral compass. As he sunk deeper into the morass of his own evil, the movie built to a gruesome pitch. The ghost of his poisoned wife, her face bubbled with sores and blood, being nailed to a shutter by him and sunk in the fetid swamp, only to float up and haunt him, seemed to be the story's only way of making him face the horrors he had committed. And she kept appearing throughout the third act--on the ceiling, in mirrors, behind curtains, etc. Yet, throughout the film he seemed incapable of feeling any human emotion or conscience about his crimes until finally at the end he is forced to suffer the consequences of his own actions.
Revenge is definitely the theme of this movie, but carried out in a way both cinematically and artistically that I had never seen before on screen. I loved this movie.
Ben M. mentioned that modern directors of Japanese horror films, such as Ju-on (The Grudge), Ringu (The Ring) and Honogurai mizu no soko kara (Dark Water) cited Nakagama as part of their inspiration. I have seen the original Japanese versions of these 3 movies (not the American remakes) and can certainly say that the influences of "Ghost Story" can be seen in all.
The two Japanese imports on TCM really scared me and thrilled me and that's a good indication of real horror.