There’s a lot of life left in Ajin as a story, no question about that. The anime may or may not ever continue, but in terms of the premise it feels as if we’ve barely scratched the surface. We know so little about the Ajin phenomenon itself for starters, and the character arcs for most of the major players are largely unfinished. So when it comes to OVAs like this one, there’s plenty of grist for the mill – and Satou’s past is certainly as good a place to go as any.
I will say this much – I’m a bit confused about what Satou’s actual name is. In the anime it’s revealed (eventually) to be Samuel T. O’Brien. In the manga it’s apparently “Samuel T. Owen”. But all through this OVA Samuel’s (I guess we can stipulate to that part) fellow special forces guys call him “Fox”. I’m not sure how you get from either of those options to Fox, or from Fox to Satou, but whatever moniker you lay on him, this is one messed-up dude.
As origin stories go, I think Satou’s comes pretty close to what most people would have imagined and filled in the blanks with. A special forces soldier (Army Rangers, maybe? Nah – Special Ops I think…) who doesn’t do too well with social niceties and is a bit of a loose cannon. Fascinated with the whole concept of Ajin (his unit is involved in what may be the first capture of one). Kind of a psychopath in waiting. It’s when his unit is stationed somewhere in the Mideast (Iraq, I believe) that the shit really hits the fan with Fox, and the course of human history is changed.
Satou is right of course – the rub with the whole Ajin thing is “you never know till you die”. They look like us, act more of less like us… As a super-soldier utterly bored with his job, the idea of being an Ajin is so seductive that Fox is almost willing to take the ultimate test – and indeed, some time after he’s dishonorably discharged for going rogue during a mission (his team is so efficient that Fox is bored even more) he effectively does just that. For someone of Satou’s temperament and intelligence – a restless and brilliant badass who cares for nothing except the game – being an Ajin is the greatest gift available. An unending supply of extra lives. It’s exactly where the Satou we knew as a great anti-hero seems as if he would have come from, and that makes this origin story about as authentic as you could hope for.