a scifi(?) anime i don't know the name of

i watched this i believe possibly off of most likely netflix or even hulu but it could be something else maybe 4-10 years ago

it was an anime where most of the main characters were unremarkable but each had different brightly colored hair, they lived in a city/town of some kind 

on the outside of the town was an empty space kind of like a desert that the characters would go into while wearing special suits to protect them from something there, the most notable thing i remember was their helmets looked kind of a bit like motorcycle helmets and that they had weapons

the main danger in the desert area was big structures that became hostile and had like bloody flowery looking things from them, i remember specifically a scene where one of the bloody flowery things got an unnamed person outside of the main character in one of the suits in a sort of prologue-flashback not part of the main story thing, and blood filled the head of their helmet. they'd reappear later sort of possessed by the entity or whatever it was and would attack the main characters, there mightve been multiple of these human entity agents but i remember at least one

the main goal of the characters was to reach a place called ground or base zero where the monster infection thing was at its worst. inside someone found a girl inside of a bloody jellyfish thing and talked to her to make everything go back to normal 

one of the characters had green hair and one had orange-ish hair

the ground zero place was overrun by the evil structure thing but other than that it was kind of high tech looking along with the decay