This OAV sequel takes place about a year after the original TV series ended. Miaka and Taka (formerly known as Tamahome) are enjoying a happy relationship, but of course that's not going to last. Someone opens the magical "Universe of the Four Gods" book again and a whole new can of worms emerges. A demon god who feeds on despair has in it for the happy couple and thus they get sucked back to Konan to reunite with the Suzaku Seven and hopefully once again bring peace and balance to both worlds.
On the plus side, this follow-up OAV does a good job of advancing the characters. Since it takes place a year after the TV series ended, you get to see how things have changed. Miaka and Taka's relationship continues to develop, and something I didn't expect is that Yui and Tetsuya are now going out. I tend to like that kind of thing because you get to see what happens after the "happily ever after" ending.
Other than that though, this did little to improve my overall opinion of the series. The plot here gets confusing at times, and little explanation is given for a lot of the stuff that happens. For example, the characters jump from the book-world to the real-world and back again multiple times during the course of the 9 episodes, which was strange in itself, but also made me wonder why it was so difficult for the characters to do before (in the TV series). I was also confused by just what was going on with the the previously-thought-dead characters. The deceased members of the Suzaku Seven can still hang around in spirit form, but they could occasionally gain a solid body, but it's never satisfactorily explained why. And then there is the issue of Tamahome/Taka who has been "reborn" in Miaka's world, but instead of being a new born baby, he appears to be the same age as when he died. In general, the story just seems to go in whatever direction it wants and gives little regard to explaining why things happen.
The cast of characters is the same as in the TV series, save for the demon and a scattering of supporting cast members. And as with the TV series, most of them don't do much of anything (Chiriko is still as useless as ever). One thing that is nice though is that you finally get to see the origin of Chichiri's scar. That alone almost makes the OAV worth watching -- at least it does if you are desperate to find a reason.
The art, animation, and music were about on par with the original TV series: average. So nothing new on that front.
As with the TV series, the ending was satsifying. It was climactic and emotional, and we get to see some change in Miaka and Taka's relationship. And it would have been great if it all just ended there and I could go on with my life, but no. I still have a 4-episode OAV on left to watch and then it will all be done with. I've come this far, so I guess there's no sense in stopping now.