Here is a sumary what i see from a readers perspective.
There is a virus originating from mars. Its the N5S virus.
Human infected with the virus stop aging, but the mind is destroyed and they are hideously deformed.
Infectees are called drones and they are basically the equivalent of zombies.
Infection is via spores that are somehow generated by the drones.
There are people who are immune to the virus, they are called adaptees. It seems we never get to see one. We know that synthetic humans are immune (thats why Loew´s agent from V survived in a the drone-infected district).
EDIT: drones are not only attracted to Yion Green but also to the MSCF
on 9JO because the adaptees, the DRF found, were held there.
The first two villains, the Patrolofficer and the PHS agent (?) are basically cyborgs, with super strength, extra toughness, weapons build in the body and a jet pack in their back.
But because the DRF found adaptees and was able to do some succesful research, they were able to give their people new powers.
The first thing we see, is the patrol-officer who was able to regenerate a head-shot and after applying a liquid, is transformed into a human giant.
Of course Zouichi defeated him
In chapter12 we learn from Dr. Kurokawa´s daughter, called the mother, that the N5S virus leaked out from a labaratory and thus everybody on mars was infected, except for one person. Apparently an adaptee.
The colony was destroyed because of the drones.
Until then we were made to believe that Yion Green is an adaptee, but in chapter 13 Fuyu discovers that she was never infected.
We also know that drones are mysteriously attracted to Yion. Maybe that is because her pollen could re-transform them to their original state.
In chapter 13 we learn from Taira what she and Gou were able to steal from the DRF:
the latest version of pseudo N5S. A less poisonous version of the virus, which applied to humans, makes them immune to the drone-hazard and enables them with the super-regenerative healing power.
In the same chapter, Taira and Kozlov meet Higuide, he is shot in the head by Nishu, but re-appears in chapter 14, with the head wound regenerating.
He also survives being almost sliced in half in the duel with Nyaldee´s spy. So obviously Higuide is a benefitor of pseudo N5S.
I chapter 15, we see Kardal for the first time. She is kind of the Biomega-version of the Abara superheroes.
Also Narain is introduced. He looks like an alien octopus and has some kind of telepathic/telekinetic power, with which he kills one of his agents.
In chapter 16, more CEU freaks are introduced, but only the most „normal“ plays a bigger role, ending in a duel with Higuide, because he is a spy for Nyaldee.
In chapter 20 we witness what the R.P.I.P. is and does (turn drones into protoplasm). We also learn that Loew knew about it and sealed it away, before he disappeared.
Here we have an inconsistency: Loew´s agent says he disappeared 186 years ago, but in chapter 19, Fuyu says he disappeared 608 years ago...
In chapter 21 we see Kardal transforming from the usual PHS suit´n´tie plus apron into her „spiderman“-combat-dress.
In chapter 22, we see the strange spikey „warbirds“ for the first time.
In chapter 24, Narain is killed but resurrected by applying pseudo N5S to his synthetic human body. he gains the power to turn drones back into humans.
In chapter25 we learn that Narain knows about Yion Green´s pollen and what is does.