I'll try to handle this with only minor spoilers. "Rasen" is an alternate version of "Ringu 2" in some ways. Both begin shortly after "Ringu" (one day for "Rasen," one week for "Ringu 2"). Both have most of the main cast of "Ringu" and much of the supporting cast, and use or recreate many locations and sets, believably portraying the immediate aftermath of the prior film's conclusion. Lastly, both place a large emphasis on Takano Mai, Takayama Ryuuji's student who is implied to have an intimate relationship with him in "Ringu" (in "Rasen" it's established that they were lovers, in "Ringu 2" she had a crush on him which he didn't reciprocate), who has E.S.P. (which wasn't even hinted at in "Ringu"). But "Rasen" and "Ringu 2" are mutually exclusive. Neither is consistent with the other, nor is "Ringu 2" (made only a year later) a remake of "Rasen"). Basically things diverge into two different fictional universes at the end of "Ringu" (both are consistent with "Ringu 0," or at least the parts of "Ringu 0" that I understood). I haven't read any of the books or short stories, so I don't know which of the sequels, if either, has a is based on one. The Wikipedia is of no help, since one page says "Rasen" is based on the written sequel to "Ringu" and "Ringu 2" has no literary basis, while another page says the opposite.
Our protagonist is Mitsuo Andou, a somewhat unhinged colleague and friend to Takayama Ryuuji. He's not in "Ringu," but his insertion into continuity isn't awkward. The rest of the cast is mostly from "Ringu." Ryuuji has lots of screen time, despite being dead.
In a totally random digression, Takayama Ryuuji's full name is said numerous times in the first three minutes of the movie, and it's unintentionally funny. It reminds me of a similar thing in "The Godfather, Part III" with Joey Zasa.
The first half hour of "Ringu 2" is little more than a recap of "Ringu." Two different people synopsize it, and there are lots of flashbacks. Actually, there are lots of flashbacks in the remaining hour, too. To "Ringu," to other backstory, and to earlier parts of this film. Some are shown twice, one is shown three times. Most are unnecessary, and even the helpful ones are usually worked in awkwardly. But back to what I was saying: Over a third of the movie is over before anything really happens, and much of the next third is superfluous. At about the one hour mark, Mai's E.S.P. is revealed, her and Andou begin having an amorous relationship completely out of the blue, and the real story kicks in. This is also where it all starts to fall apart because, once the movie gets past all the creepy set-pieces and recaps of "Ringu," all that's left is the plot. And the plot is pretty bad.
I won't spoil things by going into too much detail, but it's about what Sadako's ghost does once it's released from the well. Basically getting its revenge on the world in ways that weren't remotely suggested in "Ringu." The videotape ceases to be important. I don't think anything explicitly contradicts anything in "Ringu," but it doesn't feel true to its spirit. And the speed at which this plot unfolds is still remarkably slow, because there are more flashbacks, more unnecessary exposition and restatement, and scenes that play out much longer than necessary. Of course, even if you remove the padding, it's still a silly little runaround with people doing things for the sake of the plot rather than any realistic motivation. By the end, I really didn't care anymore, and was mainly just watching in case I would have to know some of this to understand "Ringu 2" (at that point I didn't realize "Ringu 2" wasn't any kind of sequel to "Rasen").
The high point of this movie, without a doubt, is Andou's vision of the dissected Ryuuji coming to life during his autopsy. It's an incredibly realistic effect, and truly chilling. Not for the faint of heart, yet still the only good reason to watch "Rasen." Watch the other three as a trilogy and forget this one. Four out of ten might be a little generous, but on the other hand it seemed to be a good movie for well over half its length.
Our protagonist is Mitsuo Andou, a somewhat unhinged colleague and friend to Takayama Ryuuji. He's not in "Ringu," but his insertion into continuity isn't awkward. The rest of the cast is mostly from "Ringu." Ryuuji has lots of screen time, despite being dead.
In a totally random digression, Takayama Ryuuji's full name is said numerous times in the first three minutes of the movie, and it's unintentionally funny. It reminds me of a similar thing in "The Godfather, Part III" with Joey Zasa.
The first half hour of "Ringu 2" is little more than a recap of "Ringu." Two different people synopsize it, and there are lots of flashbacks. Actually, there are lots of flashbacks in the remaining hour, too. To "Ringu," to other backstory, and to earlier parts of this film. Some are shown twice, one is shown three times. Most are unnecessary, and even the helpful ones are usually worked in awkwardly. But back to what I was saying: Over a third of the movie is over before anything really happens, and much of the next third is superfluous. At about the one hour mark, Mai's E.S.P. is revealed, her and Andou begin having an amorous relationship completely out of the blue, and the real story kicks in. This is also where it all starts to fall apart because, once the movie gets past all the creepy set-pieces and recaps of "Ringu," all that's left is the plot. And the plot is pretty bad.
I won't spoil things by going into too much detail, but it's about what Sadako's ghost does once it's released from the well. Basically getting its revenge on the world in ways that weren't remotely suggested in "Ringu." The videotape ceases to be important. I don't think anything explicitly contradicts anything in "Ringu," but it doesn't feel true to its spirit. And the speed at which this plot unfolds is still remarkably slow, because there are more flashbacks, more unnecessary exposition and restatement, and scenes that play out much longer than necessary. Of course, even if you remove the padding, it's still a silly little runaround with people doing things for the sake of the plot rather than any realistic motivation. By the end, I really didn't care anymore, and was mainly just watching in case I would have to know some of this to understand "Ringu 2" (at that point I didn't realize "Ringu 2" wasn't any kind of sequel to "Rasen").
The high point of this movie, without a doubt, is Andou's vision of the dissected Ryuuji coming to life during his autopsy. It's an incredibly realistic effect, and truly chilling. Not for the faint of heart, yet still the only good reason to watch "Rasen." Watch the other three as a trilogy and forget this one. Four out of ten might be a little generous, but on the other hand it seemed to be a good movie for well over half its length.