The show began with following a basically-loser-teenaged protagonist, with many of the typical traits of one: rash, bullheaded, naive, reckless, complete idiot, and in this case, also a wimp. (You know the type.) He somehow landed in a local jail, where he met a woman.
Said woman decided to, on a whim, show him some kindness, but was blunt about her nature and who she is. Essentially, a rebel biker/street racer, the like, in that she has zero respect for authority, she does all sorts of illicit activities (in jail she was openly whoring herself out for cash; she asked the protagonist if he had a problem with that, but she also does drugs and the like), she knows how to fight both in melee and with guns, the like. (You know the type.)
However, the protagonist ends up released thanks to who he is (which is left unspecified), and mentions that thanks to him using the influence of his mother, he decided to leverage things such that the woman would go free. She stays reasonably clean...for a while, but then she goes on what amounts to an incredibly destructive rampage, one which happens to also leave a bloody mess behind.
She shows no signs of slowing down, until she is suddenly shot in the stomach...by the protagonist. Except, the protagonist looks entirely different. His eyes have gone from the wide idealist to the narrow stone-cold serious look, and there's no emotion in them. She barely even recognizes him, but can tell that it's still him, and is confused, as she passes out.
We then get introduced to a bunch of characters who have ties to the protagonist, wherein it is essentially shown some more supernatural elements are involved. (For a start, they're all aliens/demons of a sort, whose native language is not English, so they have many quirks about them. They speak it to try and practice the language, but make the occasional mistake here and there.)
The protagonist, among their ranks, more or less in the time gap involved, had a sort-of coming-of-age, wherein he went from not being involved in their profession to being one of their more ruthless agents thanks to an unspecified trauma involved in the process.
The woman, when she recovers, is slowly introduced to this world, but mostly is wondering what the hell happened to the sweet kid she had known before. At a later point soon after, she ends up taking a bullet to save the protagonist, and for a flash of a second, she can see the old him return when he panics about what happened. After this incident, she is introduced more formally to the world, and is made to be one of their agents, partnered with the protagonist.
There, her skills would be able to be put to good use, and she would also get to know the details behind the protagonist more.
The dream was surprisingly coherent and I am doing an absolutely terrible job of explaining it. When I was "watching" the anime, it was following many typical anime patterns. The way characters were introduced, the quirks they had, the pacing of events, how things switched perspectives/scenes, all were dead on the money with how an anime focused around a particular organization with about a dozen IMPORTANT members would treat their cast.
This also means that even I don't know all the details. I only know the details as they were given to me in the show. The dream was keeping me from being spoiled about anything too major. There was a potential hint that demonic possession was implied to be a thing and that the organization fights the things who possess people, but I didn't get far enough into the dream to confirm.
It was really good, and I wish I could explain to others just how good it was.