Ju On 2

Ju-On 2 starts at the beginning of the first film, re-telling the story that started it all in the original Ju-On (a teacher goes to check on his young student, ends up finding the mother has been murdered and the kid is three steps from ok and well, after a call from the father telling him he’s just murdered the teacher’s wife and unborn child, and then things get rough when the kid, Toshio, starts meowing like a cat and the mom crawls down the stairs for the teacher she has obsessed about for so long. And then about half way into the film the new story picks up. The sequel follows the curse, or the grudge if you translate what Ju-On means, as it takes more victims. This time it is the owner of the house that Toshio and his mother, the two main ghosts, had lived, that finds the curse upon he and his family, his sister going mad and their parents both being killed. Another angle the story follows is that of a school boy the landlord’s son, that has so far survived the grudge but finds himself followed by the spirits to his school, where they soon possess, or so it would seem, all the children at the school. The film ends with the grudge still unfulfilled and growing still…waiting for more victims. Source

To fully understand this movie, you need to see the first one. Believe me, it's worthy of your time. I saw it in the dark, alone and it really freaked me out. The plot is more dense and scarier, the make-up and the special FX are far more better than the first Ju On.