The plot is about what you'd expect after surviving the likes of Police and Girl and all the rest of the viscera-splattered likes of his merrie madmen-in-company. After a meteorite crash-lands on Earth, it spreads a strange ash that causes those who breathe it to become flesh-eating monsters (the "fast zombies" of 28 Days Laterand Doomsday), and causes a sociopathic cannibal woman to become their hive queen. Her daughter survives having her heart ripped out only to be transformed into a chain-katana-wielding anti-zombie weapon, whom the government enlists along with a bunch of other lowlifes into entering the Infected Zone north of Tokyo and taking out said queen.
Like all of other Nishimura's projects, the movie is at heart just a grand excuse to show one outlandish scene after another. What about the scene where the heroes' car is bombarded with severed zombie heads — which is just the setup for an even bigger punchline, namely where they're coming from in the first place? (Here's a hint: it involves baseball.) Or the car made entirely out of zombie flesh? Or the climax involving a giant B-52 bomber made out of .... but I wouldn't dream of ruining that joke.
Almost all this stuff features at least one instance per scene of Nishimura's signature shot, which is someone screaming while being showered with oceans of blood from some offscreen source, for what feels like minutes on end. "Minutes on end" is unfortunately a good way to describe the way most every scene in the film plays out — it's about half an hour longer than it deserves to be, mostly because of pacing issues that turn every one-beat moment into five, for no particular good reason. A shame, because that approach takes what could have been a far nimbler, sassier film and turns it into a bit of a grinding drag.
There is a part of me that wants to take this film with me into a time machine back to 1989, show it to Shinya Tsukamoto right after he created Tetsuo: The Iron Man and shout at him "See what you're responsible for?" I suspect he would have approved.