Bible Black: New Testament retains the majority of characters from Bible Black, the glaring exception being Minase (who's mentioned once, and even then is fate is vague), and introduces an antagonist that's even more sinister than Kitami.
In the vicinity of the old school, several mysterious murders take place, the one common element being a female apparition reported. The police bring in their psychic division, including Kurumi Imari, to investigate. One of the deceased is rumored to hold a piece of the Lance of Longinus (For this that don't know, little history lesson here. The Lance is a spear used by the Roman soldier Longinus to pierce Jesus while he we crucified; it's long been said to possess a mystical property, and it's most notorious use came when it was held by the Nazi's during the second world war).
Meanwhile, Kaori Saeki, now a teacher at the school, starts up another witchcraft club (you'd think she'd learn by now, considering the final scene of the original series...), while Rika Shiraki is working their. Hiroko Takashiro is now a nun, and seems to maintain a friendship with Rika.
Regarding the events of the original series, Takashiro says she managed to seal Kitami's spirit away in Imari; while Saeki, Takashiro and Shiraki remember those events, Imari has no memory of it, and is not aware that Kitami is inside her.
Now, back to the plot; Imari finds out that the dead professor kept his piece of the spear in a bank vault, so Imari goes in under cover to retrieve it, only to walk into a robbery/hostage situation. Imari's taken to the back where an impromptu ritual takes place, allowing Kitami to take over Imari's body.
At this point, the entire story becomes confusing as hell to me, with the introduction of Jody Crowley, the series antagonist. Jody is the (fictional) granddaughter of (real) occultist Aleister Crowley, and her power is...well, Jody makes Kitami look like pretty Mary Sunshine. From their, the forces of evil battle the forces of....not-quite-as-evil, in a plot that I'm still trying to figure out.
I wasn't to big of a fan of this. It is much better than your average hentai, but to put this another way, Bible Black is to Rocky as BB: New Testament is to Rocky V. You're happy to see the same old faces, but it's just inferior, and leaves a lot of questions to be answered at the conclusion.
I'd suggest that as far as plot and story, that only fans of the original Bible Black watch it.
