Takashi Miike directed one of the most disturbing horror movies I have ever seen (Audition), so I like to check out some of his other work. Movie like 13 Samurai are actually pretty entertaining. This one is a horse of a different color.
Set in the world of a theater production, this movie follows the lead actress as she pulls strings to get her lesser known boyfriend a lead role in the production. As the various actors develop crushes on each other, the world of the play (which is a ghost story itself) and the real world start mingling. Before long, things go very wrong.
This is one of the few foreign films I have seen where I felt like my lack of cultural knowledge was a real hindrance. I think you would get a lot more out of this movie if you were familiar with Yotsuya Kaidan, the ghost story that is featured in the play. According to wikipedia there is all sorts of murder and subterfuge in that play which would explain some of the grisly things that go down in the last act of this movie. Miike isn't afraid of gore but it feels less horrific here than in Audition.
If you like Miike, check it out, it is worth a watch. If you are a casual viewer, I would recommend against it without some homework and a strong stomach.