This anime is the best example of an enigma, you'll see why shortly.

Reiko Mikami is an exorcist or Ghost Sweeper as she calls herself, aged 31 (start counting the Christmas Cake Jokes) With her ragtag team of misfits which includes yokai, easy to possess teens, a pastor and a Werewolf among other rival exorcists most prominently a princess with a yokai team. Mikami is all about profit and getting rich, although she's more tolerable than Inaho of Mosquiton fame.
The film's plot revolves around Nosferatu taking on the form of Oda Nobunaga and leaving modern Japan in a zombie apocalypse after an accidental awakening with Mikami's blood.
Ghost Sweeper Mikami is rare for many reasons, it's a comedy released in quite a quiet period circa 1993, for context Sailor Moon was in it's second season, Dragonballz was finishing the Cell Saga, Victory Gundam was Gundam's lowest point, Belldandy was anime's best girl and Slam Dunk was awakening a new era of fans to the concepts of Shounen Ai.
Mikami did well to remain relevant helped by a successful game run and is a staple of 90s comedy anime, it's one movie appearance brought to the west well certainly in the UK was a poor reflection of what Mikami is about, it looked way too dark and grizzly with the humour feeling forced at times although it's dub despite the early era was pretty good.
Final Verdict: Tracking down the TV series is the way to go with this franchise, the movie just sucks.